U.S. patent application number 10/789077 was filed with the patent office on 2005-09-01 for organophotoreceptor with charge transport compositions.
Invention is credited to Gaidelis, Valentas, Getautis, Vytautas, Grazulevicius, Juozas V., Jubran, Nusrallah, Malinauskas, Tadas, Montrimas, Edmundas, Tokarski, Zbigniew.
Application Number | 20050191570 10/789077 |
Document ID | / |
Family ID | 34750548 |
Filed Date | 2005-09-01 |
United States Patent
Application |
20050191570 |
Kind Code |
A1 |
Tokarski, Zbigniew ; et
al. |
September 1, 2005 |
Organophotoreceptor with charge transport compositions
Abstract
An organophotoreceptor comprises an electrically conductive
substrate and photoconductive element on the electrically
conductive substrate, the photoconductive element having a) a
charge transport composition with the formula 1 where Y.sub.1 and
Y.sub.2 are, each independently, an arylamine group; X.sub.1 and
X.sub.2 are, each independently, a linking group; R.sub.1 and
R.sub.2 are, each independently, a hydrogen, an alkyl group, an
alkenyl group, a heterocyclic group, an aromatic group; Z is a
bridging group; and n is a distribution of integers between 1 and
100,000 with an average value greater than 1; and (b) a charge
generating compound. Corresponding electrophotographic apparatuses
and imaging methods are described.
Inventors: |
Tokarski, Zbigniew;
(Woodbury, MN) ; Jubran, Nusrallah; (St. Paul,
MN) ; Getautis, Vytautas; (Kaunas, LT) ;
Grazulevicius, Juozas V.; (Kaunas, LT) ; Malinauskas,
Tadas; (Kaunas, LT) ; Montrimas, Edmundas;
(Vilnius, LT) ; Gaidelis, Valentas; (Vilnius,
LT) |
Correspondence
Address: |
PATTERSON, THUENTE, SKAAR & CHRISTENSEN, P.A.
4800 IDS CENTER
80 SOUTH 8TH STREET
MINNEAPOLIS
MN
55402-2100
US
|
Family ID: |
34750548 |
Appl. No.: |
10/789077 |
Filed: |
February 27, 2004 |
Current U.S.
Class: |
430/58.45 ;
430/74; 430/77; 548/135; 564/251 |
Current CPC
Class: |
C07D 209/86 20130101;
G03G 5/0629 20130101; G03G 5/0614 20130101; C08G 61/123 20130101;
C08G 73/0253 20130101; G03G 5/0616 20130101; C08G 61/126 20130101;
G03G 5/076 20130101; G03G 5/075 20130101; G03G 5/0633 20130101;
C08G 61/122 20130101; G03G 5/062 20130101; C07D 285/125 20130101;
C07C 323/48 20130101; C08G 73/0273 20130101; C07D 417/14
20130101 |
Class at
Publication: |
430/058.45 ;
430/074; 430/077; 548/135; 564/251 |
International
Class: |
G03G 005/06; C07D
285/14; C07C 251/80 |
Claims
What is claimed is:
1. An organophotoreceptor comprising an electrically conductive
substrate and a photoconductive element on the electrically
conductive substrate, the photoconductive element comprising: (a) a
charge transport composition having the formula 14where Y.sub.1 and
Y.sub.2 are, each independently, an arylamine group; X.sub.1 and
X.sub.2 are, each independently, a linking group; R.sub.1 and
R.sub.2 are, each independently, a hydrogen, an alkyl group, an
alkenyl group, a heterocyclic group, an aromatic group; Z is a
bridging group; and n is a distribution of integers between 1 and
100,000 with an average value greater than 1; and (b) a charge
generating compound.
2. An organophotoreceptor according to claim 1 wherein Y.sub.1 and
Y.sub.2, each independently, comprise an
(N,N-disubstituted)arylamine group, a julolidine group, or a
carbazole group.
3. An organophotoreceptor according to claim 1 wherein X.sub.1 and
X.sub.2 comprise, each independently, a --(CH.sub.2).sub.m-- group
where m is an integer between 1 and 30, inclusive, and one or more
of the methylene groups is optionally replaced by O, S, N, C, B,
Si, P, C.dbd.O, O.dbd.S.dbd.O, a heterocyclic group, an aromatic
group, an NR.sub.a group, a CR.sub.b group, a CR.sub.cR.sub.d
group, or a SiR.sub.eR.sub.f where R.sub.a, R.sub.b, R.sub.c,
R.sub.d, R.sub.e, and R.sub.f are, each independently, a bond, H, a
hydroxyl group, a thiol group, a carboxyl group, an amino group, an
alkyl group, an alkoxy group, an alkenyl group, a heterocyclic
group, an aromatic group, or part of a ring group.
4. An organophotoreceptor according to claim 3 wherein at least one
of the methylene groups is replaced by a heterocyclic group, an
aromatic group, a CHOH group, O, or S.
5. An organophotoreceptor according to claim 3 wherein the charge
transport composition has the following formula: 15where n is a
distribution of integers between 1 and 100,000; Y.sub.1 and Y.sub.2
are, each independently, an arylamine group; and T has one of the
following formulae: 16where T.sub.1, T.sub.2, T.sub.3, T.sub.4, and
T.sub.5 are, each independently, O, S, O.dbd.S.dbd.O, or
C.dbd.O.
6. An organophotoreceptor according to claim 1 wherein Z comprises
a --(CH.sub.2).sub.k-- group where k is an integer between 1 and
30, inclusive, and one or more of the methylene groups is
optionally replaced by O, S, N, C, B, Si, P, C.dbd.O,
O.dbd.S.dbd.O, a heterocyclic group, an aromatic group, an NR.sub.g
group, a CR.sub.h group, a CR.sub.iR.sub.j group, or a
SiR.sub.kR.sub.l where R.sub.g, R.sub.h, R.sub.i, R.sub.j, R.sub.k,
and R.sub.l are, each independently, a bond, H, a hydroxyl group, a
thiol group, a carboxyl group, an amino group, an alkyl group, an
alkoxy group, an alkenyl group, a heterocyclic group, an aromatic
group, or part of a ring group.
7. An organophotoreceptor according to claim 6 wherein Z has the
formulae: 17where Q is a bond, O, S, O.dbd.S.dbd.O, C.dbd.O, an
aryl group, an NR.sub.3 group, or a CR.sub.4R.sub.5 group, where
R.sub.3, R.sub.4, and R.sub.5 are, each independently, H, an alkyl
group, an alkenyl group, a heterocyclic group, an aromatic group,
or part of a ring group; and Z.sub.1, Z.sub.2, Z.sub.3, and Z.sub.4
are, each independently, a bond or a --(CH.sub.2).sub.n-- group
where n is an integer between 1 and 20, inclusive, and one or more
of the methylene groups is optionally replaced by O, S, N, C, Si,
B, P, C.dbd.O, O.dbd.S.dbd.O, a heterocyclic group, an aromatic
group, urethane, urea, an ester group, an NR.sub.6 group, a
CR.sub.7 group, a CR.sub.8R.sub.9 group, or a SiR.sub.10OR.sub.11
group, where R.sub.6, R.sub.7, R.sub.8, R.sub.9, R.sub.10, and
R.sub.11 are, each independently, a bond, H, hydroxyl, thiol,
carboxyl, an amino group, an alkyl group, an alkoxy group, an
alkenyl group, a heterocyclic group, an aromatic group, or part of
a ring group.
8. An organophotoreceptor according to claim 7 wherein Z has the
formula: 18where Q is O.dbd.S.dbd.O, and Z.sub.1 and Z.sub.2 are,
each independently, a bond.
9. An organophotoreceptor according to claim 1 wherein the
photoconductive element further comprises a second charge transport
material.
10. An organophotoreceptor according to claim 9 wherein the second
charge transport material comprises an electron transport
compound.
11. An organophotoreceptor according to claim 1 wherein the
photoconductive element further comprises a polymer binder.
12. An electrophotographic imaging apparatus comprising: (a) a
light imaging component; and (b) an organophotoreceptor oriented to
receive light from the light imaging component, the
organophotoreceptor comprising an electrically conductive substrate
and a photoconductive element on the electrically conductive
substrate, the photoconductive element comprising: (i) a charge
transport composition having the formula 19where Y.sub.1 and
Y.sub.2 are, each independently, an arylamine group; X.sub.1 and
X.sub.2 are, each independently, a linking group; R.sub.1 and
R.sub.2 are, each independently, a hydrogen, an alkyl group, an
alkenyl group, a heterocyclic group, an aromatic group; Z is a
bridging group; and n is a distribution of integers between 1 and
100,000 with an average of greater than 1; and (ii) a charge
generating compound.
13. An electrophotographic imaging apparatus according to claim 12
wherein Y.sub.1 and Y.sub.2, each independently, comprise an
(N,N-disubstituted)arylamine group, a julolidine group, or a
carbazole group.
14. An electrophotographic imaging apparatus according to claim 12
wherein X.sub.1 and X.sub.2 comprise, each independently, a
--(CH.sub.2).sub.m-- group where m is an integer between 1 and 30,
inclusive, and one or more of the methylene groups is optionally
replaced by O, S, N, C, B, Si, P, C.dbd.O, O.dbd.S.dbd.O, a
heterocyclic group, an aromatic group, an NR.sub.a group, a
CR.sub.b group, a CR.sub.cR.sub.d group, or a SiR.sub.eR.sub.f
where R.sub.a, R.sub.b, R.sub.c, R.sub.d, R.sub.e, and R.sub.f are,
each independently, a bond, H, a hydroxyl group, a thiol group, a
carboxyl group, an amino group, an alkyl group, an alkoxy group, an
alkenyl group, a heterocyclic group, an aromatic group, or part of
a ring group.
15. An electrophotographic imaging apparatus according to claim 14
wherein at least one of the methylene groups is replaced by a
heterocyclic group, an aromatic group, a CHOH group, O, or S
16. An electrophotographic imaging apparatus according to claim 12
wherein Z comprises a --(CH.sub.2).sub.k-- group where k is an
integer between 1 and 30, inclusive, and one or more of the
methylene groups is optionally replaced by O, S, N, C, B, Si, P,
C.dbd.O, O.dbd.S.dbd.O, a heterocyclic group, an aromatic group, an
NR.sub.g group, a CR.sub.h group, a CR.sub.iR.sub.j group, or a
SiR.sub.kR.sub.l where R.sub.g, R.sub.h, R.sub.i, R.sub.j, R.sub.k,
and R.sub.l are, each independently, a bond, H, a hydroxyl group, a
thiol group, a carboxyl group, an amino group, an alkyl group, an
alkoxy group, an alkenyl group, a heterocyclic group, an aromatic
group, or part of a ring group
17. An electrophotographic imaging apparatus according to claim 16
wherein Z has the formulae: 20where Q is a bond, O, S,
O.dbd.S.dbd.O, C.dbd.O, an aryl group, an NR.sub.3 group, or a
CR.sub.4R.sub.5 group, where R.sub.3, R.sub.4, and R.sub.5 are,
each independently, H, an alkyl group, an alkenyl group, a
heterocyclic group, an aromatic group, or part of a ring group; and
Z.sub.1, Z.sub.2, Z.sub.3, and Z.sub.4 are, each independently, a
bond or a --(CH.sub.2).sub.n-- group where n is an integer between
1 and 20, inclusive, and one or more of the methylene groups is
optionally replaced by O, S, N, C, Si, B, P, C.dbd.O,
O.dbd.S.dbd.O, a heterocyclic group, an aromatic group, urethane,
urea, an ester group, an NR.sub.6 group, a CR.sub.7 group, a
CR.sub.8R.sub.9 group, or a SiR.sub.10R.sub.11 group, where
R.sub.6, R.sub.7, R.sub.8, R.sub.9, R.sub.10, and R.sub.11 are,
each independently, a bond, H, hydroxyl, thiol, carboxyl, an amino
group, an alkyl group, an alkoxy group, an alkenyl group, a
heterocyclic group, an aromatic group, or part of a ring group.
18. An electrophotographic imaging apparatus according to claim 17
wherein Z has the formula: 21where Q is O.dbd.S.dbd.O, and Z.sub.1
and Z.sub.2 are, each independently, a bond.
19. An electrophotographic imaging apparatus according to claim 12
wherein the photoconductive element further comprises an electron
transport compound.
20. An electrophotographic imaging apparatus according to claim 12
wherein the photoconductive element further comprises a binder.
21. An electrophotographic imaging apparatus according to claim 12
further comprising a toner dispenser.
22. An electrophotographic imaging process comprising: (a) applying
an electrical charge to a surface of an organophotoreceptor
comprising an electrically conductive substrate and a
photoconductive element on the electrically conductive substrate,
the photoconductive element comprising: (i) a charge transport
composition having the formula 22where Y.sub.1 and Y.sub.2 are,
each independently, an arylamine group; X.sub.1 and X.sub.2 are,
each independently, a linking group; R.sub.1 and R.sub.2 are, each
independently, a hydrogen, an alkyl group, an alkenyl group, a
heterocyclic group, an aromatic group; Z is a bridging group; and n
is a distribution of integers between 1 and 100,000 with an average
greater than 1; and (ii) a charge generating compound; (b)
imagewise exposing the surface of the organophotoreceptor to
radiation to dissipate charge in selected areas and thereby form a
pattern of charged and uncharged areas on the surface; (c)
contacting the surface with a toner to create a toned image; and
(d) transferring the toned image to a substrate.
23. An electrophotographic imaging process according to claim 22
wherein Y.sub.1 and Y.sub.2, each independently, comprise an
(N,N-disubstituted)arylamine group, a julolidine group, or a
carbazole group.
24. An electrophotographic imaging process according to claim 22
wherein X.sub.1 and X.sub.2 comprise, each independently, a
--(CH.sub.2).sub.m-- group where m is an integer between 1 and 30,
inclusive, and one or more of the methylene groups is optionally
replaced by O, S, N, C, B, Si, P, C.dbd.O, O.dbd.S.dbd.O, a
heterocyclic group, an aromatic group, an NR.sub.a group, a
CR.sub.b group, a CR.sub.cR.sub.d group, or a SiR.sub.eR.sub.f
where R.sub.a, R.sub.b, R.sub.c, R.sub.d, R.sub.e, and R.sub.f are,
each independently, a bond, H, a hydroxyl group, a thiol group, a
carboxyl group, an amino group, an alkyl group, an alkoxy group, an
alkenyl group, a heterocyclic group, an aromatic group, or part of
a ring group.
25. An electrophotographic imaging process according to claim 22
wherein Z comprises a --(CH.sub.2).sub.k-- group where k is an
integer between 1 and 30, inclusive, and one or more of the
methylene groups is optionally replaced by O, S, N, C, B, Si, P,
C.dbd.O, O.dbd.S.dbd.O, a heterocyclic group, an aromatic group, an
NR.sub.g group, a CR.sub.h group, a CR.sub.iR.sub.j group, or a
SiR.sub.kR.sub.l where R.sub.g, R.sub.h, R.sub.i, R.sub.j, R.sub.k,
and R.sub.l are, each independently, a bond, H, a hydroxyl group, a
thiol group, a carboxyl group, an amino group, an alkyl group, an
alkoxy group, an alkenyl group, a heterocyclic group, an aromatic
group, or part of a ring group.
26. An electrophotographic imaging process according to claim 22
wherein the photoconductive element further comprises an electron
transport compound.
27. An electrophotographic imaging process according to claim 20
wherein the toner comprises a toner comprising colorant
particles.
28. A charge transport composition having the formula: 23where
Y.sub.1 and Y.sub.2 are, each independently, an arylamine group;
X.sub.1 and X.sub.2 are, each independently, a linking group;
R.sub.1 and R.sub.2 are, each independently, a hydrogen, an alkyl
group, an alkenyl group, a heterocyclic group, an aromatic group; Z
is a bridging group; and n is a distribution of integers between 1
and 100,000 with an average greater than 1.
29. A charge transport composition according to claim 28 wherein
Y.sub.1 and Y.sub.2, each independently, comprise an
(N,N-disubstituted)arylamine group, a julolidine group, or a
carbazole group.
30. A charge transport composition according to claim 28 wherein
X.sub.1 and X.sub.2 comprise, each independently, a
--(CH.sub.2).sub.m-- group where m is an integer between 1 and 30,
inclusive, and one or more of the methylene groups is optionally
replaced by O, S, N, C, B, Si, P, C.dbd.O, O.dbd.S.dbd.O, a
heterocyclic group, an aromatic group, an NR.sub.a group, a
CR.sub.b group, a CR.sub.cR.sub.d group, or a SiR.sub.eR.sub.f
where R.sub.a, R.sub.b, R.sub.c, R.sub.d, R.sub.e, and R.sub.f are,
each independently, a bond, H, a hydroxyl group, a thiol group, a
carboxyl group, an amino group, an alkyl group, an alkoxy group, an
alkenyl group, a heterocyclic group, an aromatic group, or part of
a ring group.
31. A charge transport composition according to claim 30 wherein at
least one of the methylene groups is replaced by a heterocyclic
group, an aromatic group, a CHOH group, O, or S.
32. A charge transport composition according to claim 30 wherein
the charge transport composition has the following formula: 24where
n is a distribution of integers between 1 and 100,000 with an
average value greater than 1; Y.sub.1 and Y.sub.2 are, each
independently, an arylamine group; and T has one of the following
formulae: 25where T.sub.1, T.sub.2, T.sub.3, T.sub.4, and T.sub.5
are, each independently, O, S, O.dbd.S.dbd.O, or C.dbd.O.
33. A charge transport composition according to claim 28 wherein Z
comprises a --(CH.sub.2).sub.k-- group where k is an integer
between 1 and 30, inclusive, and one or more of the methylene
groups is optionally replaced by O, S, N, C, B, Si, P, C.dbd.O,
O.dbd.S.dbd.O, a heterocyclic group, an aromatic group, an NR.sub.g
group, a CR.sub.h group, a CR.sub.iR.sub.j group, or a
SiR.sub.kR.sub.l where R.sub.g, R.sub.h, R.sub.i, R.sub.j, R.sub.k,
and R.sub.l are, each independently, a bond, H, a hydroxyl group, a
thiol group, a carboxyl group, an amino group, an alkyl group, an
alkoxy group, an alkenyl group, a heterocyclic group, an aromatic
group, or part of a ring group.
34. A charge transport composition according to claim 33 wherein Z
has the formulae: 26where Q is a bond, O, S, O.dbd.S.dbd.O,
C.dbd.O, an aryl group, an NR.sub.3 group, or a CR.sub.4R.sub.5
group, where R.sub.3, R.sub.4, and R.sub.5 are, each independently,
H, an alkyl group, an alkenyl group, a heterocyclic group, an
aromatic group, or part of a ring group; and Z.sub.1, Z.sub.2,
Z.sub.3, and Z.sub.4 are, each independently, a bond or a
--(CH.sub.2).sub.n-- group where n is an integer between 1 and 20,
inclusive, and one or more of the methylene groups is optionally
replaced by O, S, N, C, Si, B, P, C.dbd.O, O.dbd.S.dbd.O, a
heterocyclic group, an aromatic group, urethane, urea, an ester
group, an NR.sub.6 group, a CR.sub.7 group, a CR.sub.8R.sub.9
group, or a SiR.sub.10R.sub.11 group, where R.sub.6, R.sub.7,
R.sub.8, R.sub.9, R.sub.10, and R.sub.11 are, each independently, a
bond, H, hydroxyl, thiol, carboxyl, an amino group, an alkyl group,
an alkoxy group, an alkenyl group, a heterocyclic group, an
aromatic group, or part of a ring group.
35. A charge transport composition according to claim 34 wherein Z
has the formulae: 27where Q is O.dbd.S.dbd.O, and Z.sub.1 and
Z.sub.2 are, each independently, a bond.
36. A charge transport composition prepared by co-polymerizing a
multi-functional compound comprising at least 2 active hydrogens
selected form the group consisting of hydroxyl hydrogen, amino
hydrogen, carboxyl hydrogen, and thiol hydrogen with a
reactive-ring compound having the following formula 28where Y.sub.1
and Y.sub.2 are, each independently, an arylamine group; X.sub.3
and X.sub.4, each independently, comprise a --(CH.sub.2).sub.p--
group, where p is an integer between 1 and 20, inclusive, and one
or more of the methylene groups is optionally replaced by O, S, N,
C, B, Si, P, C.dbd.O, O.dbd.S.dbd.O, a heterocyclic group, an
aromatic group, an NR.sub.m group, a CR.sub.n group, a
CR.sub.oR.sub.p group, or a SiR.sub.qR.sub.r where R.sub.m,
R.sub.n, R.sub.o, R.sub.p, R.sub.q, and R.sub.r are, each
independently, a bond, H, a hydroxyl group, a thiol group, a
carboxyl group, an amino group, an alkyl group, an alkoxy group, an
alkenyl group, a heterocyclic group, an aromatic group, or part of
a ring group; R.sub.1 and R.sub.2 are, each independently, a
hydrogen, an alkyl group, an alkenyl group, a heterocyclic group,
an aromatic group; Z comprises a --(CH.sub.2).sub.k-- group where k
is an integer between 1 and 30, inclusive, and one or more of the
methylene groups is optionally replaced by O, S, N, C, B, Si, P,
C.dbd.O, O.dbd.S.dbd.O, a heterocyclic group, an aromatic group, an
NR.sub.g group, a CR.sub.h group, a CR.sub.iR.sub.j group, or a
SiR.sub.kR.sub.l where R.sub.g, R.sub.h, R.sub.i, R.sub.j, R.sub.k,
and R.sub.l are, each independently, a bond, H, a hydroxyl group, a
thiol group, a carboxyl group, an amino group, an alkyl group, an
alkoxy group, an alkenyl group, a heterocyclic group, an aromatic
group, or part of a ring group; and E.sub.1 and E.sub.2 are, each
independently, a reactive ring group.
37. A charge transport composition according to claim 36 wherein
E.sub.1 and E.sub.2, each independently, are selected from the
group consisting of 3-, 4-, 5-, 7-, 8-, 9-, 10-, 11-, and
12-membered heterocyclic ring groups.
38. A charge transport composition according to claim 36 wherein
E.sub.1 and E.sub.2, each independently, are selected from the
group consisting of 3-, 4-, 5-, 7-, 8-, 9-, 10-, 11-, and
12-membered cyclic ethers, cyclic amines, cyclic sulfides, cyclic
amides, N-carboxy-a-amino acid anhydrides, lactones, and
cyclosiloxanes.
39. A charge transport composition according to claim 36 wherein
E.sub.1 and E.sub.2, each independently, are selected from the
group consisting of epoxides, oxetanes, aziridines, thiiranes,
2-azetidinone, 2-pyrrolidone, 2-piperidone, caprolactam,
enantholactam, and capryllactam.
40. A charge transport composition according to claim 36 wherein
the multi-functional compound is selected from the group consisting
of triols, triamines, trithiols, diols, dithiols, diamines,
dicarboxlyic acids, hydroxylamines, amino acids, hydroxyl acids,
thiol acids, hydroxythiosl, and thioamines.
Description
FIELD OF THE INVENTION
[0001] This invention relates to organophotoreceptors suitable for
use in electrophotography and, more specifically, to
organophotoreceptors having a charge transport composition or a
polymeric charge transport material comprising a polymer having
repeating units comprising two hydrazone groups bonded together
through a bridging group.
BACKGROUND OF THE INVENTION
[0002] In electrophotography, an organophotoreceptor in the form of
a plate, disk, sheet, belt, drum or the like having an electrically
insulating photoconductive element on an electrically conductive
substrate is imaged by first uniformly electrostatically charging
the surface of the photoconductive layer, and then exposing the
charged surface to a pattern of light. The light exposure
selectively dissipates the charge in the illuminated areas where
light strikes the surface, thereby forming a pattern of charged and
uncharged areas, referred to as a latent image. A liquid or dry
toner is then provided in the vicinity of the latent image, and
toner droplets or particles deposit in the vicinity of either the
charged or uncharged areas to create a toned image on the surface
of the photoconductive layer. The resulting toned image can be
transferred to a suitable ultimate or intermediate receiving
surface, such as paper, or the photoconductive layer can operate as
an ultimate receptor for the image. The imaging process can be
repeated many times to complete a single image, for example, by
overlaying images of distinct color components or effect shadow
images, such as overlaying images of distinct colors to form a full
color final image, and/or to reproduce additional images.
[0003] Both single layer and multilayer photoconductive elements
have been used. In single layer embodiments, a charge transport
composition and charge generating material are combined with a
polymeric binder and then deposited on the electrically conductive
substrate. In multilayer embodiments, the charge transport material
and charge generating material are present in the element in
separate layers, each of which can optionally be combined with a
polymeric binder, deposited on the electrically conductive
substrate. Two arrangements are possible for a two-layer
photoconductive element. In one two-layer arrangement (the "dual
layer" arrangement), the charge-generating layer is deposited on
the electrically conductive substrate and the charge transport
layer is deposited on top of the charge generating layer. In an
alternate two-layer arrangement (the "inverted dual layer"
arrangement), the order of the charge transport layer and charge
generating layer is reversed.
[0004] In both the single and multilayer photoconductive elements,
the purpose of the charge generating material is to generate charge
carriers (i.e., holes and/or electrons) upon exposure to light. The
purpose of the charge transport material is to accept at least one
type of these charge carriers and transport them through the charge
transport layer in order to facilitate discharge of a surface
charge on the photoconductive element. The charge transport
material can be a charge transport compound, an electron transport
compound, or a combination of both. When a charge transport
compound is used, the charge transport compound accepts the hole
carriers and transports them through the layer with the charge
transport compound. When an electron transport compound is used,
the electron transport compound accepts the electron carriers and
transports them through the layer with the electron transport
compound.
[0005] Organophotoreceptors may be used for both dry and liquid
electrophotography. There are many differences between dry and
liquid electrophotography. A significant difference is that a dry
toner is used in dry electrophotography, whereas a liquid toner is
used in liquid electrophotography. A potential advantage of liquid
electrophotography is that it can provide a higher resolution and
thus sharper images than dry electrophotography because liquid
toner particles can be generally significantly smaller than dry
toner particles. As a result of their smaller size, liquid toners
are able to provide images of higher optical density than dry
toners.
[0006] In both dry and liquid electrophotography, the charge
transport material used for the organophotoreceptor should be
compatible with the polymeric binder in the photoconductive
element. The selection of a suitable polymeric binder for a
particular charge transport material can place constraints on the
formation of the photoconductive element. If the charge transport
material is not compatible with the polymeric binder, the charge
transport material may phase-separate or crystallize in the
polymeric binder matrix, or may diffuse onto the surface of the
layer containing the charge transport material. If such
incompatibility occurs, the organophotoreceptor can cease to
transport charges.
[0007] Furthermore, liquid electrophotography faces an additional
issue. In particular, the organophotoreceptor for liquid
electrophotography is in contact with the liquid carrier of a
liquid toner while the toner dries or pending transfer to a
receiving surface. As a result, the charge transport material in
the photoconductive element may be removed by extraction by the
liquid carrier. Over a long period of operation, the amount of the
charge transport material removed by extraction may be significant
and, therefore, detrimental to the performance of the
organophotoreceptor.
SUMMARY OF THE INVENTION
[0008] This invention provides organophotoreceptors having good
electrostatic properties such as high V.sub.acc and low V.sub.dis.
This invention also provides polymeric charge transport
compositions having reduced extraction by liquid carriers and
reducing the need for a polymeric binder.
[0009] In a first aspect, an organophotoreceptor comprises an
electrically conductive substrate and a photoconductive element on
the electrically conductive substrate, the photoconductive element
comprising
[0010] a) a charge transport composition having the formula: 2
[0011] where Y.sub.1 and Y.sub.2 are, each independently, an
arylamine group;
[0012] X.sub.1 and X.sub.2 are, each independently, a linking
group, such as a --(CH.sub.2).sub.m-- group, where m is an integer
between 1 and 30, inclusive, and one or more of the methylene
groups is optionally replaced by O, S, N, C, B, Si, P, C.dbd.O,
O.dbd.S.dbd.O, a heterocyclic group, an aromatic group, an NR.sub.a
group, a CR.sub.b group, a CR.sub.cR.sub.d group, or a
SiR.sub.eR.sub.f where R.sub.a, R.sub.b, R.sub.c, R.sub.d, R.sub.e,
and R.sub.f are, each independently, a bond, H, a hydroxyl group, a
thiol group, a carboxyl group, an amino group, an alkyl group, an
alkoxy group, an alkenyl group, a heterocyclic group, an aromatic
group, or part of a ring group;
[0013] R.sub.1 and R.sub.2 are, each independently, a hydrogen, an
alkyl group, an alkenyl group, a heterocyclic group, an aromatic
group;
[0014] Z is a bridging group, such as a --(CH.sub.2).sub.k-- group
where k is an integer between 1 and 30, inclusive, and one or more
of the methylene groups is optionally replaced by O, S, N, C, B,
Si, P, C.dbd.O, O.dbd.S.dbd.O, a heterocyclic group, an aromatic
group, an NR.sub.g group, a CR.sub.h group, a CR.sub.iR.sub.j
group, or a SiR.sub.kR.sub.l where R.sub.g, R.sub.h, R.sub.i,
R.sub.j, R.sub.k, and R.sub.l are, each independently, a bond, H, a
hydroxyl group, a thiol group, a carboxyl group, an amino group, an
alkyl group, an alkoxy group, an alkenyl group, a heterocyclic
group, an aromatic group, or part of a ring group; and
[0015] n is a distribution of integers between 1 and 100,000 with
an average value of greater than one; and
[0016] (b) a charge generating compound.
[0017] The asterisks (*) indicate terminal groups on the polymer,
which may vary between different polymer units depending on the
state of the particular polymerization process at the end of the
polymerization step.
[0018] The organophotoreceptor may be provided in the form of a
plate, a flexible belt, a flexible disk, a sheet, a rigid drum, or
a sheet around a rigid or compliant drum. In one embodiment, the
organophotoreceptor includes: (a) a photoconductive element
comprising the charge transport composition, the charge generating
compound, a second charge transport material, and a polymeric
binder; and (b) the electrically conductive substrate.
[0019] In a second aspect, the invention features an
electrophotographic imaging apparatus that includes (a) a light
imaging component; and (b) the above-described organophotoreceptor
oriented to receive light from the light imaging component. The
apparatus preferably further includes a toner dispenser, such as
liquid toner dispenser. The method of electrophotographic imaging
with photoreceptors containing these novel charge transport
compounds is also described.
[0020] In a third aspect, the invention features an
electrophotographic imaging process that includes (a) applying an
electrical charge to a surface of the above-described
organophotoreceptor; (b) imagewise exposing the surface of the
organophotoreceptor to radiation to dissipate charge in selected
areas and thereby form a pattern of at least relatively charged and
uncharged areas on the surface; (c) contacting the surface with a
toner, such as a liquid toner that includes a dispersion of
colorant particles in an organic liquid, to create a toned image;
and (d) transferring the toned image to a substrate.
[0021] In a fourth aspect, the invention features desirable charge
transport compositions having Formula (I) above.
[0022] These photoreceptors can be used successfully with toners,
such as liquid and dry toners, to produce high quality images. The
high quality of the imaging system is maintained after repeated
cycling.
[0023] Other features and advantages of the invention will be
apparent from the following description of the preferred
embodiments thereof, and from the claims.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0024] An organophotoreceptor as described herein has an
electrically conductive substrate and a photoconductive element
comprising a charge generating compound and a charge transport
composition or a polymeric charge transport material having
repeating units comprising two hydrazone groups bonded together
through a bridging group. The charge transport composition can have
desirable properties for use within organophotoreceptors for
electrophotography. In particular, the charge transport composition
of this invention can have low solubility in carrier liquid and
good compatibility with various binder materials, can be
incorporated in both the single and multilayer photoconductive
elements, and can possess excellent electrophotographic properties.
The organophotoreceptors according to this invention generally can
have a high photosensitivity, a low residual potential, and a high
stability with respect to cycle testing, crystallization, and
organophotoreceptor bending and stretching. The
organophotoreceptors are particularly useful in laser printers and
the like as well as photocopiers, scanners and other electronic
devices based on electrophotography. The use of these polymeric
charge transport materials is described in more detail below in the
context of laser printer use, although their application in other
devices operating by electrophotography can be generalized from the
discussion below.
[0025] To produce high quality images, particularly after multiple
cycles, it is desirable for the charge transport materials to form
a homogeneous solution with the polymeric binder and remain
approximately homogeneously distributed through the
organophotoreceptor material during the cycling of the material. In
addition, it is desirable to increase the amount of charge that the
charge transport material can accept (indicated by a parameter
known as the acceptance voltage or "V.sub.acc"), and to reduce
retention of that charge upon discharge (indicated by a parameter
known as the discharge voltage or "V.sub.dis").
[0026] The charge transport materials can be classified as charge
transport compound or electron transport compound. There are many
charge transport compounds and electron transport compounds known
in the art for electrophotography. Non-limiting examples of charge
transport compounds include, for example, pyrazoline derivatives,
fluorene derivatives, oxadiazole derivatives, stilbene derivatives,
enamine derivatives, enamine stilbene derivatives, hydrazone
derivatives, carbazole hydrazone derivatives, triaryl amines,
polyvinyl carbazole, polyvinyl pyrene, polyacenaphthylene, or
multi-hydrazone compounds comprising at least two hydrazone groups
and at least two groups selected from the group consisting of
arylamines such as (N,N-disubstituted)arylamines and heterocycles
such as carbazole, julolidine, phenothiazine, phenazine,
phenoxazine, phenoxathiin, thiazole, oxazole, isoxazole,
dibenzo(1,4)dioxine, thianthrene, imidazole, benzothiazole,
benzotriazole, benzoxazole, benzimidazole, quinoline, isoquinoline,
quinoxaline, indole, indazole, pyrrole, purine, pyridine,
pyridazine, pyrimidine, pyrazine, triazole, oxadiazole, tetrazole,
thiadiazole, benzisoxazole, benzisothiazole, dibenzofuran,
dibenzothiophene, thiophene, thianaphthene, quinazoline, or
cinnoline.
[0027] Generally, an electron transport compound has an electron
affinity that is large relative to potential electron traps while
yielding an appropriate electron mobility in a composite with a
polymer. In some embodiments, the electron transport compound has a
reduction potential less than O.sub.2. In general, electron
transport compounds are easy to reduce and difficult to oxidize
while charge transport compounds generally are easy to oxidize and
difficult to reduce. In some embodiments, the electron transport
compounds have a room temperature, zero field electron mobility of
at least about 1.times.10.sup.-13 cm.sup.2/Vs, in further
embodiments at least about 1.times.10.sup.-10 cm.sup.2/Vs, in
additional embodiments at least about 1.times.10.sup.-8
cm.sup.2/Vs, and in other embodiments at least about
1.times.10.sup.-6 cm.sup.2/Vs. A person of ordinary skill in the
art will recognize that other ranges of electron mobility within
the explicit ranges are contemplated and are within the present
disclosure.
[0028] Non-limiting examples of electron transport compounds
include, for example, bromoaniline, tetracyanoethylene,
tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone,
2,4,5,7-tetranitro-9-fluorenone, 2,4,5,7-tetranitroxanthone,
2,4,8-trinitrothioxanthone,
2,6,8-trinitro-indeno4H-indeno[1,2-b]thiophene-4-one, and
1,3,7-trinitrodibenzo thiophene-5,5-dioxide,
(2,3-diphenyl-1-indenylidene- )malononitrile,
4H-thiopyran-1,1-dioxide and its derivatives such as
4-dicyanomethylene-2,6-diphenyl-4H-thiopyran-1,1-dioxide,
4-dicyanomethylene-2,6-di-m-tolyl-4H-thiopyran-1,1-dioxide, and
unsymmetrically substituted 2,6-diaryl-4H-thiopyran-1,1-dioxide
such as
4H-1,1-dioxo-2-(p-isopropylphenyl)-6-phenyl-4-(dicyanomethylidene)thiopyr-
an and
4H-1,1-dioxo-2-(p-isopropylphenyl)-6-(2-thienyl)-4-(dicyanomethylid-
ene)thiopyran, derivatives of phospha-2,5-cyclohexadiene,
alkoxycarbonyl-9-fluorenylidene)malononitrile derivatives such as
(4-n-butoxycarbonyl-9-fluorenylidene)malononitrile,
(4-phenethoxycarbonyl-9-fluorenylidene)malononitrile,
(4-carbitoxy-9-fluorenylidene)malononitrile, and
diethyl(4-n-butoxycarbon- yl-2,7-dinitro-9-fluorenylidene)malonate,
anthraquinodimethane derivatives such as
11,11,12,12-tetracyano-2-alkylanthraquinodimethane and
11,11-dicyano-12,12-bis(ethoxycarbonyl)anthraquinodimethane,
anthrone derivatives such as
1-chloro-10-[bis(ethoxycarbonyl)methylene]anthrone,
1,8-dichloro-10-[bis(ethoxy carbonyl) methylene]anthrone,
1,8-dihydroxy-10-[bis(ethoxycarbonyl)methylene]anthrone, and
1-cyano-10-[bis(ethoxycarbonyl)methylene]anthrone,
7-nitro-2-aza-9-fluroenylidenemalononitrile, diphenoquinone
derivatives, benzoquinone derivatives, naphtoquinone derivatives,
quinine derivatives, tetracyanoethylenecyanoethylene,
2,4,8-trinitrothioxantone, dinitrobenzene derivatives,
dinitroanthracene derivatives, dinitroacridine derivatives,
nitroanthraquinone derivatives, dinitroanthraquinone derivatives,
succinic anhydride, maleic anhydride, dibromomaleic anhydride,
pyrene derivatives, carbazole derivatives, hydrazone derivatives,
N,N-dialkylaniline derivatives, diphenylamine derivatives,
triphenylamine derivatives, triphenylmethane derivatives,
tetracyanoquinodimethane, 2,4,5,7-tetranitro-9-fluorenone,
2,4,7-trinitro-9-dicyanomethylenefluorenone,
2,4,5,7-tetranitroxanthone derivatives, 2,4,8-trinitrothioxanthone
derivatives, 1,4,5,8-naphthalene bis-dicarboximide derivatives as
described in U.S. Pat. Nos. 5,232,800, 4,468,444, and 4,442,193 and
phenylazoquinolide derivatives as described in U.S. Pat. No.
6,472,514. In some embodiments of interest, the electron transport
compound comprises an (alkoxycarbonyl-9-fluorenylidene)malononi-
trile derivative, such as
(4-n-butoxycarbonyl-9-fluorenylidene)malononitri- le, and
1,4,5,8-naphthalene bis-dicarboximide derivatives.
[0029] Although there are many charge transport materials
available, there is a need for other charge transport materials to
meet the various requirements of particular electrophotography
applications. Polymeric charge transport materials have the
potential advantage of being less physically mobile within a
polymer binder. In particular, if the polymeric charge transport
material is compatible with the polymer binder, the polymers can
entangle with each other such that the polymeric charge transport
material is much less susceptible to extraction by a liquid carrier
associated with a liquid toner or the like.
[0030] In electrophotography applications, a charge-generating
compound within an organophotoreceptor absorbs light to form
electron-hole pairs. These electrons and holes can be transported
over an appropriate time frame under a large electric field to
discharge locally a surface charge that is generating the field.
The discharge of the field at a particular location results in a
surface charge pattern that essentially matches the pattern drawn
with the light. This charge pattern then can be used to guide toner
deposition. The polymeric charge transport materials described
herein can be effective at transporting charge, holes and/or
electrons, from the electron-hole pairs formed by the charge
generating compound. In some embodiments, a specific electron
transport compound or charge transport compound can also be used
along with the polymeric charge transport material of this
invention.
[0031] The layer or layers of materials containing the charge
generating compound and the charge transport materials are within
an organophotoreceptor. To print a two dimensional image using the
organophotoreceptor, the organophotoreceptor has a two dimensional
surface for forming at least a portion of the image. The imaging
process then continues by cycling the organophotoreceptor to
complete the formation of the entire image and/or for the
processing of subsequent images.
[0032] The organophotoreceptor may be provided in the form of a
plate, a flexible belt, a disk, a rigid drum, a sheet around a
rigid or compliant drum, or the like. The charge transport material
can be in the same layer as the charge generating compound and/or
in a different layer from the charge generating compound.
Additional layers can be used also, as described further below.
[0033] In some embodiments, the organophotoreceptor material
comprises, for example: (a) a charge transport layer comprising the
polymeric charge transport material and a polymeric binder; (b) a
charge generating layer comprising the charge generating compound
and a polymeric binder; and (c) the electrically conductive
substrate. The charge transport layer may be intermediate between
the charge generating layer and the electrically conductive
substrate. Alternatively, the charge generating layer may be
intermediate between the charge transport layer and the
electrically conductive substrate. In further embodiments, the
organophotoreceptor material has a single layer with both a charge
transport material and a charge generating compound within a
polymeric binder.
[0034] The organophotoreceptors can be incorporated into an
electrophotographic imaging apparatus, such as laser printers. In
these devices, an image is formed from physical embodiments and
converted to a light image that is scanned onto the
organophotoreceptor to form a surface latent image. The surface
latent image can be used to attract toner onto the surface of the
organophotoreceptor, in which the toner image is the same or the
negative of the light image projected onto the organophotoreceptor.
The toner can be a liquid toner or a dry toner. The toner is
subsequently transferred, from the surface of the
organophotoreceptor, to a receiving surface, such as a sheet of
paper. After the transfer of the toner, the entire surface is
discharged, and the material is ready to cycle again. The imaging
apparatus can further comprise, for example, a plurality of support
rollers for transporting a paper receiving medium and/or for
movement of the photoreceptor, a light imaging component with
suitable optics to form the light image, a light source, such as a
laser, a toner source and delivery system and an appropriate
control system.
[0035] An electrophotographic imaging process generally can
comprise (a) applying an electrical charge to a surface of the
above-described organophotoreceptor; (b) imagewise exposing the
surface of the organophotoreceptor to radiation to dissipate charge
in selected areas and thereby form a pattern of charged and
uncharged areas on the surface; (c) exposing the surface with a
toner, such as a liquid toner that includes a dispersion of
colorant particles in an organic liquid to create a toner image, to
attract toner to the charged or discharged regions of the
organophotoreceptor; and (d) transferring the toner image to a
substrate.
[0036] As described herein, an organophotoreceptor comprises a
charge transport composition comprising molecules having the
formula 3
[0037] where Y.sub.1 and Y.sub.2 are, each independently, an
arylamine group;
[0038] X.sub.1 and X.sub.2 are, each independently, a linking
group, such as a --(CH.sub.2).sub.m-- group, where m is an integer
between 1 and 30, inclusive, and one or more of the methylene
groups is optionally replaced by O, S, N, C, B, Si, P, C.dbd.O,
O.dbd.S.dbd.O, a heterocyclic group, an aromatic group, an NR.sub.a
group, a CR.sub.b group, a CR.sub.cR.sub.d group, or a
SiR.sub.eR.sub.f where R.sub.a, R.sub.b, R.sub.c, R.sub.d, R.sub.e,
and R.sub.f are, each independently, a bond, H, a hydroxyl group, a
thiol group, a carboxyl group, an amino group, an alkyl group, an
alkoxy group, an alkenyl group, a heterocyclic group, an aromatic
group, or part of a ring group;
[0039] R.sub.1 and R.sub.2 are, each independently, a hydrogen, an
alkyl group, an alkenyl group, a heterocyclic group, an aromatic
group;
[0040] Z is a bridging group, such as a --(CH.sub.2).sub.k-- group
where k is an integer between 1 and 30, inclusive, and one or more
of the methylene groups is optionally replaced by O, S, N, C, B,
Si, P, C.dbd.O, O.dbd.S.dbd.O, a heterocyclic group, an aromatic
group, an NR.sub.g group, a CR.sub.h group, a CR.sub.iR.sub.j
group, or a SiR.sub.kR.sub.l where R.sub.g, R.sub.h, R.sub.i,
R.sub.j, R.sub.k, and R.sub.l are, each independently, a bond, H, a
hydroxyl group, a thiol group, a carboxyl group, an amino group, an
alkyl group, an alkoxy group, an alkenyl group, a heterocyclic
group, an aromatic group, or part of a ring group; and
[0041] n is a distribution of integers between 1 and 100,000 with
an average value of greater than one.
[0042] The arylamine group includes, but is not limited to, an
(N,N-disubstituted)arylamine group (e.g., triarylamine group,
alkyldiarylamine group, and dialkylarylamine group), a julolidine
group, and a carbazole group.
[0043] The heterocyclic group includes any monocyclic or polycyclic
(e.g., bicyclic, tricyclic, etc.) ring compound having at least a
heteroatom (e.g., O, S, N, P, B, Si, etc.) in the ring.
[0044] An aromatic group can be any conjugated ring system
containing 4n+2 pi-electrons. There are many criteria available for
determining aromaticity. A widely employed criterion for the
quantitative assessment of aromaticity is the resonance energy.
Specifically, an aromatic group has a resonance energy. In some
embodiments, the resonance energy of the aromatic group is at least
10 KJ/mol. In further embodiments, the resonance energy of the
aromatic group is greater than 0.1 KJ/mol. Aromatic groups may be
classified as an aromatic heterocyclic group which contains at
least a heteroatom in the 4n+2 pi-electron ring, or as an aryl
group which does not contain a heteroatom in the 4n+2 pi-electron
ring. The aromatic group may comprise a combination of aromatic
heterocyclic group and aryl group. Nonetheless, either the aromatic
heterocyclic or the aryl group may have at least one heteroatom in
a substituent attached to the 4n+2 pi-electron ring. Furthermore,
either the aromatic heterocyclic or the aryl group may comprise a
monocyclic or polycyclic (such as bicyclic, tricyclic, etc.)
ring.
[0045] Non-limiting examples of the aromatic heterocyclic group are
furanyl, thiophenyl, pyrrolyl, indolyl, carbazolyl, benzofuranyl,
benzothiophenyl, dibenzofuranyl, dibenzothiophenyl, pyridinyl,
pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl, tetrazinyl,
petazinyl, quinolinyl, isoquinolinyl, cinnolinyl, phthalazinyl,
quinazolinyl, quinoxalinyl, naphthyridinyl, pteridinyl, acridinyl,
phenanthridinyl, phenanthrolinyl, anthyridinyl, purinyl,
pteridinyl, alloxazinyl, phenazinyl, phenothiazinyl, phenoxazinyl,
phenoxathiinyl, dibenzo(1,4)dioxinyl, thianthrenyl, and a
combination thereof. The aromatic heterocyclic group may also
include any combination of the above aromatic heterocyclic groups
bonded together either by a bond (as in bicarbazolyl) or by a
linking group (as in 1,6 di(10H-10-phenothiazinyl)h- exane). The
linking group may include an aliphatic group, an aromatic group, a
heterocyclic group, or a combination thereof. Furthermore, either
an aliphatic group or an aromatic group within a linking group may
comprise at least one heteroatom such as O, S, Si, and N.
[0046] Non-limiting examples of the aryl group are phenyl,
naphthyl, benzyl, or tolanyl group, sexiphenylene, phenanthrenyl,
anthracenyl, coronenyl, and tolanylphenyl. The aryl group may also
include any combination of the above aryl groups bonded together
either by a bond (as in biphenyl group) or a linking group (as in
stilbenyl, diphenyl sulfone, an arylamine group). The linking group
may include an aliphatic group, an aromatic group, a heterocyclic
group, or a combination thereof. Furthermore, either an aliphatic
group or an aromatic group within a linking group may comprise at
least one heteroatom such as O, S, Si, and N.
[0047] Substitution is liberally allowed on the chemical groups to
affect various physical effects on the properties of the compounds,
such as mobility, sensitivity, solubility, stability, and the like,
as is known generally in the art. In the description of chemical
substituents, there are certain practices common to the art that
are reflected in the use of language. The terms groups, central
nucleus, and moiety have defined meanings. The term group indicates
that the generically recited chemical entity (e.g., alkyl group,
phenyl group, aromatic group, heterocyclic ring group, epoxy group,
thiiranyl group, and aziridinyl group, etc.) may have any
substituent thereon which is consistent with the bond structure of
that group. For example, where the term `alkyl group` is used, that
term would not only include unsubstituted linear, branched and
cyclic alkyls, such as methyl, ethyl, isopropyl, tert-butyl,
cyclohexyl, dodecyl and the like, but also substituents having
heteroatom, such as 3-ethoxylpropyl, 4-(N,N-diethylamino)butyl,
3-hydroxypentyl, 2-thiolhexyl, 1,2,3-tribromoopropyl, and the like,
and aromatic group, such as phenyl, naphthyl, carbazolyl, pyrrole,
and the like. However, as is consistent with such nomenclature, no
substitution would be included within the term that would alter the
fundamental bond structure of the underlying group. For example,
where a phenyl group is recited, substitution such as 2- or
4-aminophenyl, 2- or 4-(N,N-disubstituted)amin- ophenyl,
2,4-dihydroxyphenyl, 2,4,6-trithiophenyl, 2,4,6-trimethoxyphenyl
and the like would be acceptable within the terminology, while
substitution of 1,1,2,2,3,3-hexamethylphenyl would not be
acceptable as that substitution would require the ring bond
structure of the phenyl group to be altered to a non-aromatic form.
Similarly, when referring to epoxy group, the compound or
substituent cited includes any substitution that does not
substantively alter the chemical nature of the epoxy ring in the
formula. When referring an (N,N-disubstituted)arylamine group, the
two substituents attached to the nitrogen may be any group that
will not substantively alter the chemical nature of the amine
group. Where the term moiety is used, such as alkyl moiety or
phenyl moiety, that terminology indicates that the chemical
material is not substituted. Where the term alkyl moiety is used,
that term represents only an unsubstituted alkyl hydrocarbon group,
whether branched, straight chain, or cyclic.
[0048] Organophotoreceptors
[0049] The organophotoreceptor may be, for example, in the form of
a plate, a sheet, a flexible belt, a disk, a rigid drum, or a sheet
around a rigid or compliant drum, with flexible belts and rigid
drums generally being used in commercial embodiments. The
organophotoreceptor may comprise, for example, an electrically
conductive substrate and on the electrically conductive substrate a
photoconductive element in the form of one or more layers. The
photoconductive element can comprise both a charge transport
material and a charge generating compound in a polymeric binder,
which may or may not be in the same layer, as well as a second
charge transport material such as a charge transport compound or an
electron transport compound in some embodiments. For example, the
charge transport material and the charge generating compound can be
in a single layer. In other embodiments, however, the
photoconductive element comprises a bilayer construction featuring
a charge generating layer and a separate charge transport layer.
The charge generating layer may be located intermediate between the
electrically conductive substrate and the charge transport layer.
Alternatively, the photoconductive element may have a structure in
which the charge transport layer is intermediate between the
electrically conductive substrate and the charge generating
layer.
[0050] The electrically conductive substrate may be flexible, for
example in the form of a flexible web or a belt, or inflexible, for
example in the form of a drum. A drum can have a hollow cylindrical
structure that provides for attachment of the drum to a drive that
rotates the drum during the imaging process. Typically, a flexible
electrically conductive substrate comprises an electrically
insulating substrate and a thin layer of electrically conductive
material onto which the photoconductive material is applied.
[0051] The electrically insulating substrate may be paper or a film
forming polymer such as polyester (e.g., polyethylene terephthalate
or polyethylene naphthalate), polyimide, polysulfone,
polypropylene, nylon, polyester, polycarbonate, polyvinyl resin,
polyvinyl fluoride, polystyrene and the like. Specific examples of
polymers for supporting substrates included, for example,
polyethersulfone (STABAR.TM. S-100, available from ICI), polyvinyl
fluoride (Tedlar.RTM., available from E.I. DuPont de Nemours &
Company), polybisphenol-A polycarbonate (MAKROFOL.TM., available
from Mobay Chemical Company) and amorphous polyethylene
terephthalate (MELINAR.TM., available from ICI Americas, Inc.). The
electrically conductive materials may be graphite, dispersed carbon
black, iodine, conductive polymers such as polypyrroles and
Calgon.RTM. conductive polymer 261 (commercially available from
Calgon Corporation, Inc., Pittsburgh, Pa.), metals such as
aluminum, titanium, chromium, brass, gold, copper, palladium,
nickel, or stainless steel, or metal oxide such as tin oxide or
indium oxide. In embodiments of particular interest, the
electrically conductive material is aluminum. Generally, the
photoconductor substrate has a thickness adequate to provide the
required mechanical stability. For example, flexible web substrates
generally have a thickness from about 0.01 to about 1 mm, while
drum substrates generally have a thickness from about 0.5 mm to
about 2 mm.
[0052] The charge generating compound is a material that is capable
of absorbing light to generate charge carriers, such as a dye or
pigment. Non-limiting examples of suitable charge generating
compounds include, for example, metal-free phthalocyanines (e.g.,
ELA 8034 metal-free phthalocyanine available from H.W. Sands, Inc.
or Sanyo Color Works, Ltd., CGM-X01), metal phthalocyanines such as
titanium phthalocyanine, copper phthalocyanine, oxytitanium
phthalocyanine (also referred to as titanyl oxyphthalocyanine, and
including any crystalline phase or mixtures of crystalline phases
that can act as a charge generating compound), hydroxygallium
phthalocyanine, squarylium dyes and pigments, hydroxy-substituted
squarylium pigments, perylimides, polynuclear quinones available
from Allied Chemical Corporation under the trade name INDOFAST.TM.
Double Scarlet, INDOFAST.TM. Violet Lake B, INDOFAST.TM. Brilliant
Scarlet and INDOFAS.TM. Orange, quinacridones available from DuPont
under the trade name MONASTRAL.TM. Red, MONASTRAL.TM. M Violet and
MONASTRAL.TM. Red Y, naphthalene 1,4,5,8-tetracarboxylic acid
derived pigments including the perinones, tetrabenzoporphyrins and
tetranaphthaloporphyrins, indigo- and thioindigo dyes,
benzothioxanthene-derivatives, perylene 3,4,9,10-tetracarboxylic
acid derived pigments, polyazo-pigments including bisazo-, trisazo-
and tetrakisazo-pigments, polymethine dyes, dyes containing
quinazoline groups, tertiary amines, amorphous selenium, selenium
alloys such as selenium-tellurium, selenium-tellurium-arsenic and
selenium-arsenic, cadmium sulphoselenide, cadmium selenide, cadmium
sulphide, and mixtures thereof. For some embodiments, the charge
generating compound comprises oxytitanium phthalocyanine (e.g., any
phase thereof), hydroxygallium phthalocyanine or a combination
thereof.
[0053] The photoconductive layer of this invention may optionally
contain a second charge transport material which may be a charge
transport compound, an electron transport compound, or a
combination of both. Generally, any charge transport compound or
electron transport compound known in the art can be used as the
second charge transport material.
[0054] An electron transport compound and a UV light stabilizer can
have a synergistic relationship for providing desired electron flow
within the photoconductor. The presence of the UV light stabilizers
alters the electron transport properties of the electron transport
compounds to improve the electron transporting properties of the
composite. UV light stabilizers can be ultraviolet light absorbers
or ultraviolet light inhibitors that trap free radicals.
[0055] UV light absorbers can absorb ultraviolet radiation and
dissipate it as heat. UV light inhibitors are thought to trap free
radicals generated by the ultraviolet light and after trapping of
the free radicals, subsequently to regenerate active stabilizer
moieties with energy dissipation. In view of the synergistic
relationship of the UV stabilizers with electron transport
compounds, the particular advantages of the UV stabilizers may not
be their UV stabilizing abilities, although the UV stabilizing
ability may be further advantageous in reducing degradation of the
organophotoreceptor over time. The improved synergistic performance
of organophotoreceptors with layers comprising both an electron
transport compound and a UV stabilizer are described further in
copending U.S. patent application Ser. No. 10/425,333 filed on Apr.
28, 2003 to Zhu, entitled "Organophotoreceptor With A Light
Stabilizer," incorporated herein by reference.
[0056] Non-limiting examples of suitable light stabilizer include,
for example, hindered trialkylamines such as Tinuvin 144 and
Tinuvin 292 (from Ciba Specialty Chemicals, Terrytown, N.Y.),
hindered alkoxydialkylamines such as Tinuvin 123 (from Ciba
Specialty Chemicals), benzotriazoles such as Tinuvan 328, Tinuvin
900 and Tinuvin 928 (from Ciba Specialty Chemicals), benzophenones
such as Sanduvor 3041 (from Clariant Corp., Charlotte, N.C.),
nickel compounds such as Arbestab (from Robinson Brothers Ltd, West
Midlands, Great Britain), salicylates, cyanocinnamates, benzylidene
malonates, benzoates, oxanilides such as Sanduvor VSU (from
Clariant Corp., Charlotte, N.C.), triazines such as Cyagard UV-1164
(from Cytec Industries Inc., N.J.), polymeric sterically hindered
amines such as Luchem (from Atochem North America, Buffalo, N.Y.).
In some embodiments, the light stabilizer is selected from the
group consisting of hindered trialkylamines having the following
formula: 4
[0057] where R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.6, R.sub.7,
R.sub.8, R.sub.10, R.sub.11, R.sub.12, R.sub.13, R.sub.14, R.sub.15
are, each independently, hydrogen, alkyl group, or ester, or ether
group; and R.sub.5, R.sub.9, and R.sub.14 are, each independently,
alkyl group; and X is a linking group selected from the group
consisting of --O--CO--(CH.sub.2).sub.m--CO--O-- where m is between
2 to 20.
[0058] Optionally, the photoconductive layer may comprise a
crosslinking agent linking the charge transport compound and the
binder. As is generally true for crosslinking agents in various
contexts, the crosslinking agent comprises a plurality of
functional groups or at least one functional group with the ability
to exhibit multiple functionality. Specifically, a suitable
crosslinking agent generally comprises at least one functional
group that reacts with an epoxy group and at least one functional
group that reacts with a functional group of the polymeric binder.
Non-limiting examples of suitable functional groups for reacting
with the epoxy group include hydroxyl, thiol, an amino group,
carboxyl group, or a combination thereof. In some embodiments, the
functional group of the crosslinking agent for reacting with the
polymeric binder does not react significantly with the epoxy group.
In general, a person of ordinary skill in the art can select the
appropriate functional group of the crosslinking agent to react
with the polymeric binder, or similarly, a person of ordinary skill
in the art can select appropriate functional groups of the
polymeric binder to react with the functional group of the
crosslinking agent. Suitable functional groups of the crosslinking
agent that do not react significantly with the epoxy group, at
least under selected conditions, include, for example, epoxy
groups, aldehydes and ketones. Suitable reactive binder functional
groups for reacting with the aldehydes and ketones include, for
example, amines.
[0059] In some embodiments, the crosslinking agent is a cyclic acid
anhydride, which effectively is at least bifunctional. Non-limiting
examples of suitable cyclic acid anhydrides include, for example,
1,8-naphthalene dicarboxylic acid anhydride, itaconic anhydride,
glutaric anhydride and citraconic anhydride, fumaric anhydride,
phthalic anhydride, isophthalic anhydride, and terephthalic
anhydride with maleic anhydride and phthalic anhydride being of
particular interest.
[0060] The binder generally is capable of dispersing or dissolving
the charge transport material (in the case of the charge transport
layer or a single layer construction), the charge generating
compound (in the case of the charge generating layer or a single
layer construction) and/or an electron transport compound for
appropriate embodiments. Examples of suitable binders for both the
charge generating layer and charge transport layer generally
include, for example, polystyrene-co-butadiene,
polystyrene-co-acrylonitrile, modified acrylic polymers, polyvinyl
acetate, styrene-alkyd resins, soya-alkyl resins,
polyvinylchloride, polyvinylidene chloride, polyacrylonitrile,
polycarbonates, polyacrylic acid, polyacrylates, polymethacrylates,
styrene polymers, polyvinyl butyral, alkyd resins, polyamides,
polyurethanes, polyesters, polysulfones, polyethers, polyketones,
phenoxy resins, epoxy resins, silicone resins, polysiloxanes,
poly(hydroxyether) resins, polyhydroxystyrene resins, novolak,
poly(phenylglycidyl ether)-co-dicyclopentadiene, copolymers of
monomers used in the above-mentioned polymers, and combinations
thereof. Specific suitable binders include, for example, polyvinyl
butyral, polycarbonate, and polyester. Non-limiting examples of
polyvinyl butyral include BX-1 and BX-5 from Sekisui Chemical Co.
Ltd., Japan. Non-limiting examples of suitable polycarbonate
include polycarbonate A which is derived from bisphenol-A (e.g.
Iupilon-A from Mitsubishi Engineering Plastics, or Lexan 145 from
General Electric); polycarbonate Z which is derived from
cyclohexylidene bisphenol (e.g. Iupilon-Z from Mitsubishi
Engineering Plastics Corp, White Plain, N.Y.); and polycarbonate C
which is derived from methylbisphenol A (from Mitsubishi Chemical
Corporation). Non-limiting examples of suitable polyester binders
include ortho-polyethylene terephthalate (e.g. OPET TR-4 from
Kanebo Ltd., Yamaguchi, Japan).
[0061] Suitable optional additives for any one or more of the
layers include, for example, antioxidants, coupling agents,
dispersing agents, curing agents, surfactants, and combinations
thereof.
[0062] The photoconductive element overall typically has a
thickness from about 10 microns to about 45 microns. In the dual
layer embodiments having a separate charge generating layer and a
separate charge transport layer, charge generation layer generally
has a thickness form about 0.5 microns to about 2 microns, and the
charge transport layer has a thickness from about 5 microns to
about 35 microns. In embodiments in which the charge transport
material and the charge generating compound are in the same layer,
the layer with the charge generating compound and the charge
transport composition generally has a thickness from about 7
microns to about 30 microns. In embodiments with a distinct
electron transport layer, the electron transport layer has an
average thickness from about 0.5 microns to about 10 microns and in
further embodiments from about 1 micron to about 3 microns. In
general, an electron transport overcoat layer can increase
mechanical abrasion resistance, increases resistance to carrier
liquid and atmospheric moisture, and decreases degradation of the
photoreceptor by corona gases. A person of ordinary skill in the
art will recognize that additional ranges of thickness within the
explicit ranges above are contemplated and are within the present
disclosure.
[0063] Generally, for the organophotoreceptors described herein,
the charge generation compound is in an amount from about 0.5 to
about 25 weight percent, in further embodiments in an amount from
about 1 to about 15 weight percent, and in other embodiments in an
amount from about 2 to about 10 weight percent, based on the weight
of the photoconductive layer. The charge transport material is in
an amount from about 10 to about 80 weight percent, based on the
weight of the photoconductive layer, in further embodiments in an
amount from about 35 to about 60 weight percent, and in other
embodiments from about 45 to about 55 weight percent, based on the
weight of the photoconductive layer. The optional second charge
transport material, when present, can be in an amount of at least
about 2 weight percent, in other embodiments from about 2.5 to
about 25 weight percent, based on the weight of the photoconductive
layer, and in further embodiments in an amount from about 4 to
about 20 weight percent, based on the weight of the photoconductive
layer. The binder is in an amount from about 15 to about 80 weight
percent, based on the weight of the photoconductive layer, and in
further embodiments in an amount from about 20 to about 75 weight
percent, based on the weight of the photoconductive layer. A person
of ordinary skill in the art will recognize that additional ranges
within the explicit ranges of compositions are contemplated and are
within the present disclosure.
[0064] For the dual layer embodiments with a separate charge
generating layer and a charge transport layer, the charge
generation layer generally comprises a binder in an amount from
about 10 to about 90 weight percent, in further embodiments from
about 15 to about 80 weight percent and in some embodiments in an
amount from about 20 to about 75 weight percent, based on the
weight of the charge generation layer. The optional charge
transport material in the charge generating layer, if present,
generally can be in an amount of at least about 2.5 weight percent,
in further embodiments from about 4 to about 30 weight percent and
in other embodiments in an amount from about 10 to about 25 weight
percent, based on the weight of the charge generating layer. The
charge transport layer generally comprises a binder in an amount
from about 20 weight percent to about 70 weight percent and in
further embodiments in an amount from about 30 weight percent to
about 50 weight percent. A person of ordinary skill in the art will
recognize that additional ranges of binder concentrations for the
dual layer embodiments within the explicit ranges above are
contemplated and are within the present disclosure.
[0065] For the embodiments with a single layer having a charge
generating compound and a charge transport material, the
photoconductive layer generally comprises a binder, a charge
transport material, and a charge generation compound. The charge
generation compound can be in an amount from about 0.05 to about 25
weight percent and in further embodiment in an amount from about 2
to about 15 weight percent, based on the weight of the
photoconductive layer. The charge transport material can be in an
amount from about 10 to about 80 weight percent, in other
embodiments from about 25 to about 65 weight percent, in additional
embodiments from about 30 to about 60 weight percent and in further
embodiments in an amount from about 35 to about 55 weight percent,
based on the weight of the photoconductive layer, with the
remainder of the photoconductive layer comprising the binder, and
optional additives, such as any conventional additives. A single
layer with a charge transport composition and a charge generating
compound generally comprises a binder in an amount from about 10
weight percent to about 75 weight percent, in other embodiments
from about 20 weight percent to about 60 weight percent, and in
further embodiments from about 25 weight percent to about 50 weight
percent. Optionally, the layer with the charge generating compound
and the charge transport material may comprise a second charge
transport material. The optional second charge transport material,
if present, generally can be in an amount of at least about 2.5
weight percent, in further embodiments from about 4 to about 30
weight percent and in other embodiments in an amount from about 10
to about 25 weight percent, based on the weight of the
photoconductive layer. A person of ordinary skill in the art will
recognize that additional composition ranges within the explicit
compositions ranges for the layers above are contemplated and are
within the present disclosure.
[0066] In general, any layer with an electron transport compound
can advantageously further include a UV light stabilizer. In
particular, the electron transport layer generally can comprise an
electron transport compound, a binder, and an optional UV light
stabilizer. An overcoat layer comprising an electron transport
compound is described further in copending U.S. patent application
Ser. No. 10/396,536 to Zhu et al. entitled, "Organophotoreceptor
With An Electron Transport Layer," incorporated herein by
reference. For example, an electron transport compound as described
above may be used in the release layer of the photoconductors
described herein. The electron transport compound in an electron
transport layer can be in an amount from about 10 to about 50
weight percent, and in other embodiments in an amount from about 20
to about 40 weight percent, based on the weight of the electron
transport layer. A person of ordinary skill in the art will
recognize that additional ranges of compositions within the
explicit ranges are contemplated and are within the present
disclosure.
[0067] The UV light stabilizer, if present, in any one or more
appropriate layers of the photoconductor generally is in an amount
from about 0.5 to about 25 weight percent and in some embodiments
in an amount from about 1 to about 10 weight percent, based on the
weight of the particular layer. A person of ordinary skill in the
art will recognize that additional ranges of compositions within
the explicit ranges are contemplated and are within the present
disclosure.
[0068] For example, the photoconductive layer may be formed by
dispersing or dissolving the components, such as one or more of a
charge generating compound, the polymeric charge transport material
of this invention, a second charge transport material such as a
charge transport compound or an electron transport compound, a UV
light stabilizer, and a polymeric binder in organic solvent,
coating the dispersion and/or solution on the respective underlying
layer and drying the coating. In particular, the components can be
dispersed by high shear homogenization, ball-milling, attritor
milling, high energy bead (sand) milling or other size reduction
processes or mixing means known in the art for effecting particle
size reduction in forming a dispersion.
[0069] The photoreceptor may optionally have one or more additional
layers as well. An additional layer can be, for example, a
sub-layer or an overcoat layer, such as a barrier layer, a release
layer, a protective layer, or an adhesive layer. A release layer or
a protective layer may form the uppermost layer of the
photoconductor element. A barrier layer may be sandwiched between
the release layer and the photoconductive element or used to
overcoat the photoconductive element. The barrier layer provides
protection from abrasion to the underlayers. An adhesive layer
locates and improves the adhesion between a photoconductive
element, a barrier layer and a release layer, or any combination
thereof. A sub-layer is a charge blocking layer and locates between
the electrically conductive substrate and the photoconductive
element. The sub-layer may also improve the adhesion between the
electrically conductive substrate and the photoconductive
element.
[0070] Suitable barrier layers include, for example, coatings such
as crosslinkable siloxanol-colloidal silica coating and
hydroxylated silsesquioxane-colloidal silica coating, and organic
binders such as polyvinyl alcohol, methyl vinyl ether/maleic
anhydride copolymer, casein, polyvinyl pyrrolidone, polyacrylic
acid, gelatin, starch, polyurethanes, polyimides, polyesters,
polyamides, polyvinyl acetate, polyvinyl chloride, polyvinylidene
chloride, polycarbonates, polyvinyl butyral, polyvinyl acetoacetal,
polyvinyl formal, polyacrylonitrile, polymethyl methacrylate,
polyacrylates, polyvinyl carbazoles, copolymers of monomers used in
the above-mentioned polymers, vinyl chloride/vinyl acetate/vinyl
alcohol terpolymers, vinyl chloride/vinyl acetate/maleic acid
terpolymers, ethylene/vinyl acetate copolymers, vinyl
chloride/vinylidene chloride copolymers, cellulose polymers, and
mixtures thereof. The above barrier layer polymers optionally may
contain small inorganic particles such as fumed silica, silica,
titania, alumina, zirconia, or a combination thereof. Barrier
layers are described further in U.S. Pat. No. 6,001,522 to Woo et
al., entitled "Barrier Layer For Photoconductor Elements Comprising
An Organic Polymer And Silica," incorporated herein by reference.
The release layer topcoat may comprise any release layer
composition known in the art. In some embodiments, the release
layer is a fluorinated polymer, siloxane polymer, fluorosilicone
polymer, silane, polyethylene, polypropylene, polyacrylate, or a
combination thereof. The release layers can comprise crosslinked
polymers.
[0071] The release layer may comprise, for example, any release
layer composition known in the art. In some embodiments, the
release layer comprises a fluorinated polymer, siloxane polymer,
fluorosilicone polymer, polysilane, polyethylene, polypropylene,
polyacrylate, poly(methyl methacrylate-co-methacrylic acid),
urethane resins, urethane-epoxy resins, acrylated-urethane resins,
urethane-acrylic resins, or a combination thereof. In further
embodiments, the release layers comprise crosslinked polymers.
[0072] The protective layer can protect the organophotoreceptor
from chemical and mechanical degradation. The protective layer may
comprise any protective layer composition known in the art. In some
embodiments, the protective layer is a fluorinated polymer,
siloxane polymer, fluorosilicone polymer, polysilane, polyethylene,
polypropylene, polyacrylate, poly(methyl
methacrylate-co-methacrylic acid), urethane resins, urethane-epoxy
resins, acrylated-urethane resins, urethane-acrylic resins, or a
combination thereof. In some embodiments of particular interest,
the release layers are crosslinked polymers.
[0073] An overcoat layer may comprise an electron transport
compound as described further in copending U.S. patent application
Ser. No. 10/396,536, filed on Mar. 25, 2003 to Zhu et al. entitled,
"Organoreceptor With An Electron Transport Layer," incorporated
herein by reference. For example, an electron transport compound,
as described above, may be used in the release layer of this
invention. The electron transport compound in the overcoat layer
can be in an amount from about 2 to about 50 weight percent, and in
other embodiments in an amount from about 10 to about 40 weight
percent, based on the weight of the release layer. A person of
ordinary skill in the art will recognize that additional ranges of
composition within the explicit ranges are contemplated and are
within the present disclosure.
[0074] Generally, adhesive layers comprise a film forming polymer,
such as polyester, polyvinylbutyral, polyvinylpyrrolidone,
polyurethane, polymethyl methacrylate, poly(hydroxy amino ether)
and the like. Barrier and adhesive layers are described further in
U.S. Pat. No. 6,180,305 to Ackley et al., entitled "Organic
Photoreceptors for Liquid Electrophotography," incorporated herein
by reference.
[0075] Sub-layers can comprise, for example, polyvinylbutyral,
organosilanes, hydrolyzable silanes, epoxy resins, polyesters,
polyamides, polyurethanes, cellulosics and the like. In some
embodiments, the sub-layer has a dry thickness between about 20
Angstroms and about 20,000 Angstroms. Sublayers containing metal
oxide conductive particles can be between about 1 and about 25
microns thick. A person of ordinary skill in the art will recognize
that additional ranges of compositions and thickness within the
explicit ranges are contemplated and are within the present
disclosure.
[0076] The polymeric charge transport materials as described
herein, and photoreceptors including these compounds, are suitable
for use in an imaging process with either dry or liquid toner
development. For example, any dry toners and liquid toners known in
the art may be used in the process and the apparatus of this
invention. Liquid toner development can be desirable because it
offers the advantages of providing higher resolution images and
requiring lower energy for image fixing compared to dry toners.
Examples of suitable liquid toners are known in the art. Liquid
toners generally comprise toner particles dispersed in a carrier
liquid. The toner particles can comprise a colorant/pigment, a
resin binder, and/or a charge director. In some embodiments of
liquid toner, a resin to pigment ratio can be from 1:1 to 10:1, and
in other embodiments, from 4:1 to 8:1. Liquid toners are described
further in Published U.S. Patent Applications 2002/0128349,
entitled "Liquid Inks Comprising A Stable Organosol," and
2002/0086916, entitled "Liquid Inks Comprising Treated Colorant
Particles," and U.S. Pat. No. 6,649,316, entitled "Phase Change
Developer For Liquid Electrophotography," all three of which are
incorporated herein by reference.
[0077] Charge Transport Composition
[0078] The organophotoreceptor described herein comprise a charge
transport composition having the formula: 5
[0079] where Y.sub.1 and Y.sub.2 are, each independently, an
arylamine group;
[0080] X.sub.1 and X.sub.2 are, each independently, a linking
group, such as a --(CH.sub.2).sub.m-- group, where m is an integer
between 1 and 30, inclusive, and one or more of the methylene
groups is optionally replaced by O, S, N, C, B, Si, P, C.dbd.O,
O.dbd.S.dbd.O, a heterocyclic group, an aromatic group, an NR.sub.a
group, a CR.sub.b group, a CR.sub.cR.sub.d group, or a
SiR.sub.eR.sub.f where R.sub.a, R.sub.b, R.sub.c, R.sub.d, R.sub.e,
and R.sub.f are, each independently, a bond, H, a hydroxyl group, a
thiol group, a carboxyl group, an amino group, an alkyl group, an
alkoxy group, an alkenyl group, a heterocyclic group, an aromatic
group, or part of a ring group;
[0081] R.sub.1 and R.sub.2 are, each independently, a hydrogen, an
alkyl group, an alkenyl group, a heterocyclic group, an aromatic
group;
[0082] Z is a bridging group, such as a --(CH.sub.2).sub.k-- group
where k is an integer between 1 and 30, inclusive, and one or more
of the methylene groups is optionally replaced by O, S, N, C, B,
Si, P, C.dbd.O, O.dbd.S.dbd.O, a heterocyclic group, an aromatic
group, an NR.sub.g group, a CR.sub.h group, a CR.sub.iR.sub.j
group, or a SiR.sub.kR.sub.l where R.sub.g, R.sub.h, R.sub.i,
R.sub.j, R.sub.k, and R.sub.l are, each independently, a bond, H, a
hydroxyl group, a thiol group, a carboxyl group, an amino group, an
alkyl group, an alkoxy group, an alkenyl group, a heterocyclic
group, an aromatic group, or part of a ring group; and
[0083] n is a distribution of integers between 1 and 100,000 with
an average value of greater than one.
[0084] In general, the distribution of n values depends on the
polymerization conditions. The presence of the polymer of formula
(1) does not preclude the presence of unreacted monomer and dimers
within the organophotoreceptor, although the concentrations of
monomers and dimers would generally be small if not extremely small
or undetectable. The extent of polymerization, as specified with n,
can affect the properties of the resulting polymer. In some
embodiments, an average value of n can be in the hundreds or
thousands, although the average value of n may be any value of 3 or
greater and in some embodiments any value of 5 or greater and in
further embodiments the average value of n is 10 or greater. A
person of ordinary skill in the art will recognize that additional
ranges of average n values are contemplated and are within the
present disclosure.
[0085] In some embodiments, the bridging group Z may comprise an
alkylene group, an alkenylene group, a heterocyclic group, or an
aromatic group. In particular, an aromatic Z group can contribute
in desirable ways to the function of the charge transport
composition. Non-limiting examples of suitable aromatic groups
include the following formulae: 6
[0086] where Q is a bond, O, S, O.dbd.S.dbd.O, C.dbd.O, an aryl
group, an NR.sub.3 group, or a CR.sub.4R.sub.5 group, where
R.sub.3, R.sub.4, and R.sub.5 are, each independently, H, an alkyl
group, an alkenyl group, a heterocyclic group, an aromatic group,
or part of a ring group; and
[0087] Z.sub.1, Z.sub.2, Z.sub.3, and Z.sub.4 are, each
independently, a bond or a --(CH.sub.2).sub.n-- group where n is an
integer between 1 and 20, inclusive, and one or more of the
methylene groups is optionally replaced by O, S, N, C, Si, B, P,
C.dbd.O, O.dbd.S.dbd.O, a heterocyclic group, an aromatic group,
urethane, urea, an ester group, an NR.sub.6 group, a CR.sub.7
group, a CR.sub.8R.sub.9 group, or a SiR.sub.10R.sub.11 group,
where R.sub.6, R.sub.7, R.sub.8, R.sub.9, R.sub.10, and R.sub.11
are, each independently, a bond, H, hydroxyl, thiol, carboxyl, an
amino group, an alkyl group, an alkoxy group, an alkenyl group, a
heterocyclic group, an aromatic group, or part of a ring group.
[0088] In some embodiments, the bridging group Z has a structure
according to Formula (II) above where Q is a O.dbd.S.dbd.O group
and Z.sub.1 and Z.sub.2 are, each independently, a bond. In further
embodiments, the charge transport composition has the following
formula: 7
[0089] where n is a distribution of integers between 1 and
100,000;
[0090] Y.sub.1 and Y.sub.2 are, each independently, an arylamine
group; and
[0091] T has one of the following formulae: 8
[0092] where T.sub.1, T.sub.2, T.sub.3, T.sub.4, and T.sub.5 are,
each independently, O, S, O.dbd.S.dbd.O, or C.dbd.O. Specific,
non-limiting examples of suitable charge transport composition
within the general Formula (I) of the present invention have the
following formulae: 9
[0093] where n is a distribution of integers between 1 and 100,000
with an average value of greater than one and the asterisks (*)
indicate terminal groups on the polymer, which may vary between
different polymer units depending on the state of the particular
polymerization process at the end of the polymerization step.
[0094] Synthesis of Charge Transport Compositions
[0095] The synthesis of the charge transport compositions of this
invention can be prepared by the following multi-step synthetic
procedure, although other suitable procedures can be used by a
person of ordinary skill in the art based on the disclosure
herein.
[0096] The charge transport composition of this invention may be
prepared by the reaction of a multi-functional compound comprising
at least 2 active hydrogens, for example, selected from the group
consisting of hydroxyl hydrogen, amino hydrogen, carboxyl hydrogen,
and thiol hydrogen with a reactive-ring compound having the
following formula 10
[0097] where Y.sub.1 and Y.sub.2 are, each independently, an
arylamine group;
[0098] X.sub.3 and X.sub.4, each independently, comprise a
--(CH.sub.2).sub.p-- group, where p is an integer between 1 and 20,
inclusive, and one or more of the methylene groups is optionally
replaced by O, S, N, C, B, Si, P, C.dbd.O, O.dbd.S.dbd.O, a
heterocyclic group, an aromatic group, an NR.sub.m group, a
CR.sub.n group, a CR.sub.oR.sub.p group, or a SiR.sub.qR.sub.r
where R.sub.m, R.sub.n, R.sub.o, R.sub.p, R.sub.q, and R.sub.r are,
each independently, a bond, H, a hydroxyl group, a thiol group, a
carboxyl group, an amino group, an alkyl group, an alkoxy group, an
alkenyl group, a heterocyclic group, an aromatic group, or part of
a ring group;
[0099] R.sub.1 and R.sub.2 are, each independently, a hydrogen, an
alkyl group, an alkenyl group, a heterocyclic group, an aromatic
group;
[0100] Z can comprise a --(CH.sub.2).sub.k-- group where k is an
integer between 1 and 30, inclusive, and one or more of the
methylene groups is optionally replaced by O, S, N, C, B, Si, P,
C.dbd.O, O.dbd.S.dbd.O, a heterocyclic group, an aromatic group, an
NR.sub.g group, a CR.sub.h group, a CR.sub.iR.sub.j group, or a
SiR.sub.kR.sub.l where R.sub.g, R.sub.h, R.sub.i, R.sub.j, R.sub.k,
and R.sub.l are, each independently, a bond, H, a hydroxyl group, a
thiol group, a carboxyl group, an amino group, an alkyl group, an
alkoxy group, an alkenyl group, a heterocyclic group, an aromatic
group, or part of a ring group; and
[0101] E.sub.1 and E.sub.2 are, each independently, a reactive ring
group, such as an epoxy ring, a thiiranyl group, an aziridinyl
group, and an oxetanyl group.
[0102] In some embodiments, the bridging group Z may comprise an
alkylene group, an alkenylene group, a heterocyclic group, or an
aromatic group. In particular, an aromatic Z group can contribute
in desirable ways to the function of the charge transport
composition. Non-limiting examples of suitable aromatic groups
include the following formulae: 11
[0103] where Q is a bond, O, S, O.dbd.S.dbd.O, C.dbd.O, an aryl
group, an NR.sub.3 group, or a CR.sub.4R.sub.5 group, where
R.sub.3, R.sub.4, and R.sub.5 are, each independently, H, an alkyl
group, an alkenyl group, a heterocyclic group, an aromatic group,
or part of a ring group; and
[0104] Z.sub.1, Z.sub.2, Z.sub.3, and Z.sub.4, each independently,
comprise a bond or a --(CH.sub.2).sub.n-- group where n is an
integer between 1 and 20, inclusive, and one or more of the
methylene groups is optionally replaced by O, S, N, C, Si, B, P,
C.dbd.O, O.dbd.S.dbd.O, a heterocyclic group, an aromatic group,
urethane, urea, an ester group, an NR.sub.6 group, a CR.sub.7
group, a CR.sub.8R.sub.9 group, or a SiR.sub.10R.sub.11 group,
where R.sub.6, R.sub.7, R.sub.8, R.sub.9, R.sub.10, and R.sub.11
are, each independently, a bond, H, hydroxyl, thiol, carboxyl, an
amino group, an alkyl group, an alkoxy group, an alkenyl group, a
heterocyclic group, an aromatic group, or part of a ring group.
[0105] The reactive ring groups, E.sub.1 and E.sub.2, are selected
from the group consisting of heterocyclic ring groups which have a
higher strain energy than its corresponding open-ring structure.
The conventional definition of strain energy is that it represents
the difference in energy between the actual molecule and a
completely strain-free molecule of the same constitution. More
information about the origin of strain energy can be found in the
article by Wiberg et al., "A Theoretical Analysis of Hydrocarbon
Properties: II Additivity of Group Properties and the Origin of
Strain Energy," J. Am. Chem. Soc. 109, 985 (1987). The above
article is incorporated herein by reference. The heterocyclic ring
group may have 3, 4, 5, 7, 8, 9, 10, 11, or 12 members, in further
embodiments 3, 4, 5, 7, or 8 members, in some embodiment 3, 4, or 8
members, and in additional embodiments 3 or 4 members. Non-limiting
examples of such heterocyclic ring are cyclic ethers (e.g.,
epoxides and oxetane), cyclic amines (e.g., aziridine), cyclic
sulfides (e.g., thiirane), cyclic amides (e.g., 2-azetidinone,
2-pyrrolidone, 2-piperidone, caprolactam, enantholactam, and
capryllactam), N-carboxy-.alpha.-amino acid anhydrides, lactones,
and cyclosiloxanes. The chemistry of the above heterocyclic rings
is described in George Odian, "Principle of Polymerization," second
edition, Chapter 7, p. 508-552 (1981), incorporated herein by
reference.
[0106] In some embodiments of interest, the reactive ring group is
an epoxy group. Some epoxy groups may have the following formula:
12
[0107] where R.sub.21, R.sub.22, and R.sub.23 are, each
independently, hydrogen, an alkyl group, an alkenyl group, or an
aromatic group (e.g. phenyl, naphthyl, carbazolyl, stilbenyl), or,
when fused together, the atoms necessary to form a 5- or 6-member
cycloaliphatic ring.
[0108] The di-epoxy-ring compound may be prepared by the following
multi-step synthetic procedure, although other suitable procedures
can be used by a person of ordinary skill in the art based on the
disclosure herein.
[0109] The first step is a nucleophilic substitution reaction
between a linking organic compound having two halogen groups (i.e.
dibromoalkanes or 4,4'-dichlorodiphenyl sulfone) and hydrazine
hydrate. The linking organic compound may or may not be symmetric
with respect to the two halogen groups. The reaction mixture may be
refluxed for 24 hours. The product of the nucleophilic substitution
is the corresponding aromatic compound having two hydrazine groups,
such as 4,4'-dihydrazinodiphenyl sulfone.
[0110] In the second step, the aromatic compound having two
hydrazine groups may react with an arylamine having an aldehyde or
a keto group to form the corresponding aromatic compound having two
hydrazone groups. If desired, two different arylamine compounds can
be reacted with the di-hydrazine compound. The use of one or two
arylamine reactants with keto groups result in a charge transport
material with R.sub.1 and/or R.sub.2 groups that differ from H.
While the use of two different arylamine compounds may result in a
mixture of products, a person of ordinary skill in the art can
reduce the synthesis of undesired forms of product through either
sequential or simultaneous reactions, and the different product
compounds can be separated from each other through appropriate
purification approaches.
[0111] In the third step, the two NH groups of the aromatic
compound having two hydrazone groups may react with an organic
halide comprising an epoxy group in the presence of an alkaline to
form a charge transport material having two epoxidated-hydrazone
groups bonded together through a linking group. Non-limiting
examples of suitable organic halide comprising an epoxy group for
this invention are epihalohydrins, such as epichlorohydrin. The
organic halide comprising an epoxy group may also be prepared by
the epoxidation reaction of the corresponding organic halide having
an olefin group. The epoxidation reaction is described in Carey et
al., "Advanced Organic Chemistry, Part B: Reactions and Synthesis,"
New York, 1983, pp. 494-498, incorporated herein by reference. The
organic halide having an olefin group may be prepared by the Wittig
reaction between a suitable organic halide having an aldehyde or
keto group and a suitable Wittig reagent. The Wittig and related
reactions are described in Carey et al., "Advanced Organic
Chemistry, Part B: Reactions and Synthesis," New York, 1983, pp.
69-77, incorporated herein by reference. Depending on the
particular reactivities of the groups, the order of some of the
reactions may be changed.
[0112] In some embodiments of interest, the E group is a thiiranyl
group. An epoxy compound, such as those described above, can be
converted into the corresponding thiiranyl compound by refluxing
the epoxy compound and ammonium thiocyanate in tetrahydrofuran.
Alternatively, the corresponding thiiranyl compound may be obtained
by passing a solution of the above-described epoxy compound through
3-(thiocyano)propyl-functionalized silica gel (commercially
available form Aldrich, Milwaukee, Wis.). Alternatively, a
thiiranyl compound may be obtained by the thia-Payne rearrangement
of a corresponding epoxy compound. The thia-Payne rearrangement is
described in Rayner, C. M. Synlett 1997, 11; Liu, Q. Y.;
Marchington, A. P.; Rayner, C. M. Tetrahedron 1997, 53, 15729;
Ibuka, T. Chem. Soc. Rev. 1998, 27, 145; and Rayner, C. M.
Contemporary Organic Synthesis 1996, 3, 499. All the above four
articles are incorporated herein by reference. For these
embodiments, X' groups can be formed, for example, using a
bifunctional group with a halogen and with a thiiranyl group. The
halide group can be replaced by a bond to the secondary amine group
of the hydrazone by a nucleophilic substitution.
[0113] In some embodiments of interest, the E group is an
aziridinyl group. An aziridine compound may be obtained by the
aza-Payne rearrangement of a corresponding epoxy compound, such as
one of those epoxy compounds described above. The thia-Payne
rearrangement is described in Rayner, C. M. Synlett 1997, 11; Liu,
Q. Y.; Marchington, A. P.; Rayner, C. M. Tetrahedron 1997, 53,
15729; and Ibuka, T. Chem. Soc. Rev. 1998, 27, 145. All the above
three articles are incorporated herein by reference. Alternatively,
an aziridine compound may be prepared by the addition reaction
between a suitable nitrene compound and a suitable alkene. Such
addition reaction is described in Carey et al., "Advanced Organic
Chemistry, Part B: Reactions and Synthesis," New York, 1983, pp.
446-448, incorporated herein by reference. For these embodiments,
X' groups can be formed, for example, using a bifunctional group
with a halogen and with an aziridinyl group. The halide group can
be replaced by a bond to the secondary amine group of the hydrazone
by a nucleophilic substitution.
[0114] In some embodiments of interest, the E group is an oxetanyl
group. An oxetane compound may be prepared by the Paterno-Buchi
reaction between a suitable carbonyl compound and a suitable
alkene. The Paterno-Buchi reaction is described in Carey et al.,
"Advanced Organic Chemistry, Part B: Reactions and Synthesis," New
York, 1983, pp. 335-336, incorporated herein by reference. For
these embodiment, X' groups can be formed, for example, using a
bifunctional group with a halogen and with an oxetanyl group. The
halide group can be replaced by a bond to the secondary amine group
of the hydrazone by a nucleophilic substitution.
[0115] For reaction with the reactive ring groups, the
multi-functional compounds, such as di-functional compounds,
tri-functional compounds, and tetra-functional compounds, may have
two or more active hydrogen atoms, such as hydroxyl hydrogen, thiol
hydrogen, amino hydrogen, and carboxyl hydrogen. The active
hydrogen atoms in any of the multi-functional compounds may be the
same or different. Non-limiting examples of tetra-functional
compounds include tetra-hydroxyl compounds, tetra-thiol compounds,
tetra-amino compounds, and tetra-carboxylic acids. Non-limiting
examples of tri-functional compounds include tri-hydroxyl
compounds, tri-thiol compounds, tri-amino compounds, and
tri-carboxylic acids. The di-functional compound may be ammonia, a
primary amine, a diol, a dithiol, a diamine, a dicarboxlyic acid, a
hydroxylamine, an amino acid, a hydroxyl acid, a thiol acid, a
hydroxythiol, or a thioamine. Non-limiting examples of suitable
dithiol are 4,4'-thiobisbenzenethiol, 1,4-benzenedithiol,
1,3-benzenedithiol, sulfonyl-bis(benzenethiol),
2,5-dimecapto-1,3,4-thiadiazole, 1,2-ethanedithiol,
1,3-propanedithiol, 1,4-butanedithiol, 1,5-pentanedithiol, and
1,6-hexanedithiol. Non-limiting examples of suitable diols are
2,2'-bi-7-naphtol, 1,4-dihydroxybenzene, 1,3-dihydroxybenzene,
10,10-bis(4-hydroxyphenyl)anthrone, 4,4 '-sulfonyldiphenol,
bisphenol, 4,4'-(9-fluorenylidene)diphenol, 1,10-decanediol,
1,5-pentanediol, diethylene glycol,
4,4'-(9-fluorenylidene)-bis(2-phenoxyethanol), bis(2-hydroxyethyl)
terephthalate, bis[4-(2-hydroxyethoxy)phenyl] sulfone,
hydroquinone-bis (2-hydroxyethyl)ether, and bis(2-hydroxyethyl)
piperazine. Non-limiting examples of suitable diamine are
diaminoarenes, and diaminoalkanes. Non-limiting examples of
suitable dicarboxylic acid are phthalic acid, terephthalic acid,
adipic acid, and 4,4'-biphenyldicarboxylic acid. Non-limiting
examples of suitable hydroxylamine are p-aminophenol and
fluoresceinamine. Non-limiting examples of suitable amino acid are
4-aminobutyric acid, phenylalanine, and 4-aminobenzoic acid.
Non-limiting examples of suitable hydroxyl acid are salicylic acid,
4-hydroxybutyric acid, and 4-hydroxybenzoic acid. Non-limiting
examples of suitable hydroxythiol are monothiohydroquinone and
4-mercapto-1-butanol. Non-limiting example of suitable thioamine is
p-aminobenzenethiol. Non-limiting example of suitable thiol acid
are 4-mercaptobenzoic acid and 4-mercaptobutyric acid. Almost all
of the above di-functional compounds are available commercially
from Aldrich Chemical Co. and other chemical suppliers.
[0116] In some embodiments, the di-functional compound may comprise
two functional groups attached to an alkylene group, an alkenylene
group, a heterocyclic group, or an aromatic group. Non-limiting
examples of suitable aromatic group include the groups having the
following formulae: 13
[0117] where Q' is a bond, O, S, O.dbd.S.dbd.O, an NR.sub.12 group,
or a CR.sub.13R.sub.14 group, where R.sub.12, R.sub.13, and
R.sub.14 are, each independently, H, an alkyl group, an alkenyl
group, a heterocyclic group, an aromatic group, or part of a ring
group; and
[0118] Z.sub.5, Z.sub.6, Z.sub.7, and Z.sub.8 are, each
independently, a bond or a --(CH.sub.2).sub.q-- group where q is an
integer between 1 and 20, inclusive, and one or more of the
methylene groups is optionally replaced by O, S, N, C, Si, B, P,
C.dbd.O, O.dbd.S.dbd.O, a heterocyclic group, an aromatic group,
urethane, urea, an ester group, an NR.sub.15 group, a CR.sub.16
group, a CR.sub.17R.sub.18 group, or a SiR.sub.19R.sub.20 group,
where R.sub.15, R.sub.16, R.sub.17, R.sub.18, R.sub.19, and
R.sub.20 are, each independently, a bond, H, hydroxyl, thiol,
carboxyl, an amino group, an alkyl group, an alkoxy group, an
alkenyl group, a heterocyclic group, an aromatic group, or part of
a ring group.
[0119] Chemical bonding between the reactive-ring compound and the
di-functional compound may be promoted by using a crossing linking
agent or an elevated reaction temperature. The reaction temperature
may be from 20.degree. C. to 200.degree. C. Preferably, the
reaction temperature is between 30.degree. C. to 100.degree. C.
[0120] Any conventional crosslinking agent for the reaction between
a reactive ring groups, such as epoxy group, and a functional
group, such as hydroxyl, thiol, carboxyl, and an amino group, known
in the art may be used for this invention. Non-limiting examples of
suitable crosslinking agent include acid anhydrides and primary or
secondary amines. Non-limiting examples of suitable acid anhydride
include 1,8-naphthalene dicarboxylic acid anhydride, itaconic
anhydride, glutaric anhydride and citraconic anhydride, fumaric
anhydride, phthalic anhydride, isophthalic anhydride, and
terephthalic anhydride with maleic anhydride and phthalic anhydride
being most preferred. Non-limiting examples of suitable primary or
secondary amines include diethylene triamine, triethylene
tetramine, m-phenylenediamine.
[0121] To synthesize the charge transport compositions, the degree
of polymerization, i.e., the average value and/or distribution of
n, is determined by the concentrations of the reactants, the
reaction conditions and the reaction time. These reaction
parameters can be adjusted by a person of ordinary skill in the
art, based on the present disclosure, to obtain desired values of
the extent of reaction. In general, if a one-to-one ratio is used
of the reactive-ring compound and the di-functional compound, the
charge transport compositions tends to comprise molecules with both
a reactive-ring end group and a functional group. A slight excess
of reactive-ring compound tends to result in a greater percentage
of the reactive-ring end group. Similarly, a slight excess of the
di-functional compound tends to result in a greater percentage of
the functional end group.
[0122] More specifically, the reactive-ring compound and the
di-functional compound react to form small molecules with more than
one repeating unit as shown in Formula (I). Under sufficiently
dilute reaction conditions and a sufficiently short reaction time,
the monomer composition effectively can be formed. To the extent
that the reaction proceeds further, small molecules can further
react with other monomer units, the reactive-ring compound and/or
di-functional compound to form larger molecules that can further
react. This reaction process continues until the reaction is
stopped. The resulting product generally can be characterized by an
average molecular weight and a distribution of molecular weights as
well as the amount of each end group. Various techniques used for
characterizing polymers generally can be used to characterize
correspondingly the polymers described herein.
[0123] In general, if a crosslinking agent is used, it may be
desirable to react the crosslinking agent first with either the
charge transport compound or with the polymer binder before
combining the other ingredients. A person of ordinary skill in the
art can evaluate the appropriate reaction order, such as combining
all of the components at one time or sequentially, for forming the
layer with desired properties.
[0124] While reactive ring groups provide a versatile synthesis
approach for the formation of the polymers described herein, other
linking groups Y of Formula (I) above can be formed using other
additive reactions that do not involve reactive ring groups. For
example, various nucleophilic substitutions can be used. Some
non-limiting examples of appropriate reactions include
esterification reactions and amidization reactions. A person of
ordinary skill in the art will recognize suitable reactive
functional groups for polymerization.
[0125] The invention will now be described further by way of the
following examples.
EXAMPLES
Example 1
Synthesis And Characterization Charge Transport Compositions
[0126] This example described the synthesis and characterization of
Compositions 1-4 in which the numbers refer to formula numbers
above. The characterization involves both chemical characterization
and the electronic characterization of materials formed with the
compound.
[0127] Composition (1)
[0128] A suspension of 4,4'-dichlorodiphenyl sulfone (20 g, 0.069
mol, obtained from Aldrich) in hydrazine hydrate (158 ml, from
Aldrich) was refluxed for 24 hours. The mixture was cooled to room
temperature and crystals precipitated out. The crystals were
filtered off and washed 3 times with water and one time with
isopropanol. The yield of the product, 4,4'-dihydrazinodiphenyl
sulfone, was 15.75 g (81.8%). The product had a melting point of
193-194.degree. C. The literature procedure for the preparation of
4,4'-dihydrazinodiphenyl sulfone was published in Khimiya
Geterotsiklicheskikh Soedinenii, 11, p.1508-1510, 1980 (issued in
the Republic of Latvia). The article is incorporated herein by
reference.
[0129] A mixture of 4-(diphenylamino)benzaldehyde (25 g, 0.09 mol,
from Aldrich), 4,4'-dihydrazinodiphenyl sulfone (11.37 g, 0.041
mol) and 80 ml of dioxane was added to a 250 ml round bottom flask
equipped with a reflux condenser and a magnetic stirrer. The
reaction mixture was heated at 50.degree. C. for 2 hours with
stirring. The solvent was removed by evaporation to form
4,4'-dihydrazondiphenyl sulfone triphenylaminohydrazone. The yield
was 30.1 g (93.4%).
[0130] A mixture of 4,4'-dihydrazondiphenyl sulfone
triphenylaminohydrazone (30.1 g, 0.038 mol) and epichlorohydrin (68
ml, 0.855 mol, obtained from Aldrich) was added to a 250 ml 3-neck
round bottom flask equipped with a reflux condenser, a thermometer
and a magnetic stirrer. The reaction mixture was stirred vigorously
at 35-40.degree. C. for 7 hours. During this time, powdered 85%
potassium hydroxide (KOH, 11.3 g, 0.171 mol) and anhydrous sodium
sulfate (Na.sub.2SO.sub.4, 9 g, 0.0228 mol) were added in three
portions with prior cooling of the reaction mixture to
20-25.degree. C. After the termination of the reaction, the mixture
was cooled to room temperature and filtered. The organic part was
treated with ethyl acetate and washed with distilled water until
the pH of the water became neutral. The organic layer was dried
over anhydrous magnesium sulfate, treated with activated charcoal,
and filtered. The solvents were evaporated to form a di-epoxide.
The di-epoxide was purified by column chromatography (silica gel,
grade 62, 60-200 mesh, 150 .ANG., Aldrich) using a mixture of
acetone and hexane in a ratio of 1:4 by volume as the eluant. The
fractions containing the di-epoxide (the Composition (1) monomer
precursor) were collected, and the solvents were evaporated. The
di-epoxide was recrystallized from a mixture of acetone and hexane
in a ratio of 1:4 by volume and dried at 50.degree. C. in a vacuum
oven for 6 hours. The yield of the di-epoxide of
4,4'-dihydrazondiphenyl sulfone triphenylaminohydrazone was 19.3 g
(56%). The product had a melting point of 223-225.degree. C. The
.sup.1H-NMR spectrum (100 MHz) of di-epoxide of
4,4'-dihydrazondiphenyl sulfone triphenylaminohydrazone in
CDCl.sub.3 was characterized by the following chemical shifts
(.delta., ppm): 8.0-6.8 (m, 38H, CH.dbd.N, Ar); 4.5-4.3 (dd, 2H,
one proton of NCH.sub.2); 4.1-3.8 (dd, 2H, another proton of
NCH.sub.2); 3.2 (m, 2H, CH); 2.9-2.8 (dd, 2H, one proton of
OCH.sub.2); 2.7-2.5 (dd, another proton of OCH.sub.2). An elemental
analysis yielded the following results in weight percent: C 74.71;
H 5.33; N 9.45, which compared with calculated values for
C.sub.38H.sub.35N.sub.5O.sub.2, in weight percent of: C 74.64; H
5.37; N 9.33.
[0131] A mixture of di-epoxide of 4,4'-dihydrazondiphenyl sulfone
triphenylaminohydrazone (1 g, 1.1 mmol, prepared in the previous
step), 4,4'-thiobisbenzenethiol (0.275 g, 1.1 mmol, obtained from
Aldrich) and 15 ml of tetrahydrofuran (THF) was added to a 50 ml
3-neck round bottom flask equipped with a reflux condenser and a
mechanical stirrer. Then, triethylamine (0.14 ml, 1.1 mmol, from
Aldrich, Milwaukee, Wis.) was added to the mixture. The mixture was
refluxed under argon for 60 hours. The reaction mixture was cooled
to room temperature and filtered through a 3-4 cm layer of silica
gel (grade 62, 60-200 mesh, 150 .ANG.). The silica gel was washed
with THF. The solution was concentrated to 15-20 ml by evaporation
and then poured into a 20-fold excess of methanol with intensive
stirring. The resulted precipitate was filtered off and washed
repeatedly with methanol and dried under a vacuum at 50.degree. C.
The yield of Composition (1) was 1.08 g (84.7%).
[0132] Composition (2)
[0133] Composition (2) may be prepared according to the procedure
for Composition (1) except that 9-ethyl-3-carbazolecarboxaldehyde
(0.09 mol) replaces 4-(diphenylamino)benzaldehyde (0.09 mol).
[0134] Composition (3)
[0135] Composition (3) was prepared according to the procedure for
Composition (1) except that 2,5-dimercapto-1,3,4-thiadiazole (0.165
g, 1.1 mmol) replaced thiobisbenzenethiol (0.275 g, 1.1 mmol). The
yield of Composition (3) was 1.01 g (86.6%).
[0136] Composition (4)
[0137] Composition (4) may be prepared according to the procedure
for Composition (2) except that 2,5-dimercapto-1,3,4-thiadiazole
(0.165 g, 1.1 mmol) replaces thiobisbenzenethiol (0.275 g, 1.1
mmol).
Example 2
Charge Mobility Measurements
[0138] This example describes the measurement of charge mobility
for samples formed with Compositions (1) and (3) described in
Example 1.
[0139] Sample 1
[0140] A mixture of 0.1 g of the Composition (1) was dissolved in 2
ml of THF. The solution was coated on the methyl cellulose coated
polyester film with conductive Al layer by the dip roller method.
After drying for 1 h at 80.degree. C., a clear 7 .mu.m thick layer
was formed. The hole mobility of the sample was measured and the
results are presented in Table 1.
[0141] Sample 2
[0142] Sample 2 was prepared and tested similarly as Sample 1,
except Composition (1) was replaced with Composition (3) and the
thickness of the coating was 4 .mu.m.
[0143] Mobility Measurements
[0144] Each sample was corona charged positively up to a surface
potential U and illuminated with 2 ns long nitrogen laser light
pulse. The hole mobility .mu. was determined as described in Kalade
et al., "Investigation of charge carrier transfer in
electrophotographic layers of chalkogenide glasses," Proceeding
IPCS 1994: The Physics and Chemistry of Imaging Systems, Rochester,
N.Y., pp. 747-752, incorporated herein by reference. The hole
mobility measurement was repeated with changes to the charging
regime to charge the sample to different U values, which
corresponded to different electric field strength inside the layer
E. This dependence on electric field strength was approximated by
the formula
.mu.=.mu..sub.0e.sup..alpha.{square root}{square root over
(E)}.
[0145] Here E is electric field strength, .mu..sub.0 is the zero
field mobility and .alpha. is Pool-Frenkel parameter. The mobility
characterizing parameters .mu..sub.0 and .alpha. values as well as
the mobility value at the 6.4.times.10.sup.5 V/cm field strength as
determined from these measurements are given in Table 1.
1TABLE 1 Ionization .mu..sub.0 .mu. (cm.sup.2/V .multidot. s)
Potential Example (cm.sup.2/V .multidot. s) at 6.4 .multidot.
10.sup.5 V/cm .alpha. (cm/V).sup.0.5 (eV) Sample 1/ 8 .multidot.
10.sup.-9 2 .multidot. 10.sup.-5 0.0098 5.49 Composition (1) Sample
2/ .about.1 .multidot. 10.sup.-8 .about.6 .multidot. 10.sup.-5
.about.0.011 5.49 Composition (3)
Example 3
Ionization Potential Measurements
[0146] This example describes the measurement of the ionization
potential for the 2 polymeric charge transport materials described
in Example 1.
[0147] To perform the ionization potential measurements, a thin
layer of polymeric charge transport material about 0.5 .mu.m
thickness was coated from a solution of 2 mg of polymeric charge
transport material in 0.2 ml of tetrahydrofuran on a 20 cm.sup.2
substrate surface. The substrate was polyester film with an
aluminum layer over a methylcellulose sublayer of about 0.4 .mu.m
thickness.
[0148] Ionization potential was measured as described in
Grigalevicius et al., "3,6-Di(N-diphenylamino)-9-phenylcarbazole
and its methyl-substituted derivative as novel hole-transporting
amorphous molecular materials," Synthetic Metals 128 (2002), p.
127-131, incorporated herein by reference. In particular, each
sample was illuminated with monochromatic light from the quartz
monochromator with a deuterium lamp source. The power of the
incident light beam was 2-5.multidot.10.sup.-8 W. A negative
voltage of -300 V was supplied to the sample substrate. A
counter-electrode with the 4.5.times.15 mm.sup.2 slit for
illumination was placed at 8 mm distance from the sample surface.
The counter-electrode was connected to the input of a BK2-16 type
electrometer, working in the open input regime, for the
photocurrent measurement. A 10.sup.-15-10.sup.-12 amp photocurrent
was flowing in the circuit under illumination. The photocurrent, I,
was strongly dependent on the incident light photon energy hv. The
I.sup.0.5=f(h.nu.) dependence was plotted. Usually, the dependence
of the square root of photocurrent on incident light quanta energy
is well described by linear relationship near the threshold (see
references "Ionization Potential of Organic Pigment Film by
Atmospheric Photoelectron Emission Analysis," Electrophotography,
28, Nr. 4, p. 364 (1989) by E. Miyamoto, Y. Yamaguchi, and M.
Yokoyama; and "Photoemission in Solids," Topics in Applied Physics,
26, 1-103 (1978) by M. Cordona and L. Ley, both of which are
incorporated herein by reference). The linear part of this
dependence was extrapolated to the h.nu. axis, and the Ip value was
determined as the photon energy at the interception point. The
ionization potential measurement has an error of .+-.0.03 eV. The
ionization potential values are given in Table 1.
[0149] As understood by those skilled in the art, additional
substitution, variation among substituents, and alternative methods
of synthesis and use may be practiced within the scope and intent
of the present disclosure of the invention. The embodiments above
are intended to be illustrative and not limiting. Additional
embodiments are within the claims. Although the present invention
has been described with reference to particular embodiments,
workers skilled in the art will recognize that changes may be made
in form and detail without departing from the spirit and scope of
the invention.
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